Add ChildMovable interface, preload filter, IsInEditorMode, lightmap init

- Add IPS_Editor_ChildMovable interface for per-child editing of sub-elements
  (VR placement spots, etc.) with full gizmo, undo, and serialization support
- Add "Edit Children" button in toolbar when a ChildMovable actor is selected
- Add bPreload tag on SpawnableComponent for briefing/placement phase actors
- Add EPS_Editor_SceneLoadFilter enum (All, PreloadOnly, ExcludePreload) to
  LoadScene for selective loading of preload vs gameplay actors
- Add bPreload field to FPS_Editor_ActorData for JSON persistence
- Add static IsInEditorMode() getter on SceneLoader (BlueprintPure)
- Add Level::InitializeRenderingResources() call on sublevel load for lightmaps
- Update Pawn, PlayerController, UndoManager, SceneSerializer, SceneLoader,
  MainWidget to support ChildMovable alongside existing SplineEditable

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Unreal/Plugins/PS_Editor/Source/PS_Editor/GameMode/PS_Editor_Pawn.cpp

@@ -15,6 +15,7 @@
 #include "PS_Editor_UndoManager.h"
 #include "PS_Editor_SplineActor.h"
 #include "PS_Editor_SplineEditable.h"
+#include "PS_Editor_ChildMovable.h"
 #include "Components/SplineComponent.h"
 #include "DrawDebugHelpers.h"
 #include "PS_Editor_ConfirmDialog.h"
@@ -380,16 +381,21 @@ void APS_Editor_Pawn::HandleLook(const FInputActionValue& Value)
 			}
 			const FVector ConstrainedDelta = DisplacementAlongAxis * AxisDir;
 
-			// Spline point mode: move the single point instead of actors
+			// Spline point / ChildMovable mode: move the single sub-element instead of actors
 			if (ActiveSplinePointIndex >= 0 && DraggedSplineActor.IsValid())
-			{
-				if (IPS_Editor_SplineEditable* SplineActor = Cast<IPS_Editor_SplineEditable>(DraggedSplineActor.Get()))
 			{
 				if (SplinePointDragInitialState.IsValidIndex(ActiveSplinePointIndex))
 				{
 					const FVector NewPos = SplinePointDragInitialState[ActiveSplinePointIndex] + ConstrainedDelta;
+
+					if (IPS_Editor_SplineEditable* SplineActor = Cast<IPS_Editor_SplineEditable>(DraggedSplineActor.Get()))
+					{
 						SplineActor->MovePoint(ActiveSplinePointIndex, NewPos);
 					}
+					else if (DraggedSplineActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+					{
+						IPS_Editor_ChildMovable::Execute_MoveChild(DraggedSplineActor.Get(), ActiveSplinePointIndex, NewPos);
+					}
 				}
 			}
 			else
@@ -475,11 +481,15 @@ void APS_Editor_Pawn::HandleLook(const FInputActionValue& Value)
 		{
 			if (ActiveSplinePointIndex >= 0 && DraggedSplineActor.IsValid())
 			{
-				// Following a single spline point
+				// Following a single spline point or child movable element
 				if (IPS_Editor_SplineEditable* SplineActor = Cast<IPS_Editor_SplineEditable>(DraggedSplineActor.Get()))
 				{
 					Gizmo->SetActorLocation(SplineActor->GetPointLocation(ActiveSplinePointIndex));
 				}
+				else if (DraggedSplineActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+				{
+					Gizmo->SetActorLocation(IPS_Editor_ChildMovable::Execute_GetChildLocation(DraggedSplineActor.Get(), ActiveSplinePointIndex));
+				}
 			}
 			else if (Selected.Num() == 1)
 			{
@@ -648,6 +658,35 @@ void APS_Editor_Pawn::HandleLeftClickStarted(const FInputActionValue& Value)
 		}
 	}
 
+	// Check for ChildMovable child handle hit
+	if (APS_Editor_PlayerController* EdPC_CM = Cast<APS_Editor_PlayerController>(GetController()))
+	{
+		if (EdPC_CM->GetEditorMode() == EPS_Editor_EditorMode::SplinePlacement)
+		{
+			AActor* ActiveActor = EdPC_CM->GetActivePlacementActor();
+			if (ActiveActor && ActiveActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+			{
+				const int32 ChildIdx = IPS_Editor_ChildMovable::Execute_GetChildIndexUnderCursor(ActiveActor, RayOrigin, RayDir);
+				if (ChildIdx >= 0)
+				{
+					ActiveSplinePointIndex = ChildIdx;
+					DraggedSplineActor = ActiveActor;
+					IPS_Editor_ChildMovable::Execute_HighlightChild(ActiveActor, ChildIdx);
+
+					if (UPS_Editor_SelectionManager* SM = EdPC_CM->GetSelectionManager())
+					{
+						if (APS_Editor_Gizmo* Gizmo = SM->GetGizmo())
+						{
+							Gizmo->SetGizmoActive(true, IPS_Editor_ChildMovable::Execute_GetChildLocation(ActiveActor, ChildIdx));
+						}
+						SM->SetTransformMode(EPS_Editor_TransformMode::Translate);
+					}
+					return;
+				}
+			}
+		}
+	}
+
 	// In SplinePlacement mode: click on spline tube mesh → insert a CP
 	if (APS_Editor_PlayerController* EdPC2 = Cast<APS_Editor_PlayerController>(GetController()))
 	{
@@ -804,13 +843,27 @@ void APS_Editor_Pawn::HandleLeftClickCompleted(const FInputActionValue& Value)
 				// Spline point drag: record SplinePointAction
 				if (ActiveSplinePointIndex >= 0 && DraggedSplineActor.IsValid())
 				{
+					TArray<FVector> NewPoints;
+					FString Desc;
+
 					if (IPS_Editor_SplineEditable* SplineActor = Cast<IPS_Editor_SplineEditable>(DraggedSplineActor.Get()))
+					{
+						NewPoints = SplineActor->GetAllPointLocations();
+						Desc = TEXT("Move spline point");
+					}
+					else if (DraggedSplineActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+					{
+						NewPoints = IPS_Editor_ChildMovable::Execute_GetAllChildLocations(DraggedSplineActor.Get());
+						Desc = TEXT("Move child element");
+					}
+
+					if (NewPoints.Num() > 0)
 					{
 						TSharedPtr<FPS_Editor_SplinePointAction> Action = MakeShared<FPS_Editor_SplinePointAction>();
-						Action->SplineActor = Cast<AActor>(SplineActor);
+						Action->SplineActor = DraggedSplineActor.Get();
 						Action->OldPoints = SplinePointDragInitialState;
-						Action->NewPoints = SplineActor->GetAllPointLocations();
+						Action->NewPoints = NewPoints;
-						Action->Description = TEXT("Move spline point");
+						Action->Description = Desc;
 						UM->RecordAction(Action);
 					}
 				}
@@ -1439,13 +1492,17 @@ void APS_Editor_Pawn::BeginGizmoDrag(EPS_Editor_GizmoAxis Axis)
 		}
 	}
 
-	// Store initial spline state if editing a point
+	// Store initial sub-element state if editing a point/child
 	if (ActiveSplinePointIndex >= 0 && DraggedSplineActor.IsValid())
 	{
 		if (IPS_Editor_SplineEditable* Spline = Cast<IPS_Editor_SplineEditable>(DraggedSplineActor.Get()))
 		{
 			SplinePointDragInitialState = Spline->GetAllPointLocations();
 		}
+		else if (DraggedSplineActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+		{
+			SplinePointDragInitialState = IPS_Editor_ChildMovable::Execute_GetAllChildLocations(DraggedSplineActor.Get());
+		}
 	}
 
 	SetCameraMode(EPS_Editor_CameraMode::GizmoDrag);

Unreal/Plugins/PS_Editor/Source/PS_Editor/GameMode/PS_Editor_PlayerController.cpp

@@ -12,6 +12,8 @@
 #include "Engine/LevelStreamingDynamic.h"
 #include "Engine/PostProcessVolume.h"
 #include "PS_Editor_CameraStart.h"
+#include "PS_Editor_ChildMovable.h"
+#include "PS_Editor_SceneLoader.h"
 #include "PS_Editor_HUD.h"
 #include "PS_Editor_MainWidget.h"
 #include "Camera/PlayerCameraManager.h"
@@ -32,6 +34,7 @@ void APS_Editor_PlayerController::BeginPlay()
 {
 	Super::BeginPlay();
 
+	UPS_Editor_SceneLoader::bIsEditorModeActive = true;
 	SetInputMode(FInputModeGameAndUI().SetHideCursorDuringCapture(false));
 
 	// AI logic will be stopped per-pawn when spawned (see SpawnManager)
@@ -190,6 +193,7 @@ void APS_Editor_PlayerController::CloseEditor()
 	}
 
 	// Notify actors: leaving editor mode
+	UPS_Editor_SceneLoader::bIsEditorModeActive = false;
 	if (SpawnManager)
 	{
 		SpawnManager->NotifyEditorModeChanged(false);
@@ -303,20 +307,29 @@ void APS_Editor_PlayerController::BeginPointPlacement(TSubclassOf<AActor> InActo
 
 void APS_Editor_PlayerController::BeginPointPlacementAppend(AActor* ExistingActor)
 {
-	if (!ExistingActor || !ExistingActor->Implements<UPS_Editor_PointPlaceable>()) return;
+	if (!ExistingActor) return;
+
+	const bool bIsPointPlaceable = ExistingActor->Implements<UPS_Editor_PointPlaceable>();
+	const bool bIsChildMovable = ExistingActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass());
+	if (!bIsPointPlaceable && !bIsChildMovable) return;
 
 	ActivePlacementActor = ExistingActor;
 	bAppendingToActor = true;
 	EditorMode = EPS_Editor_EditorMode::SplinePlacement;
 
-	// Store initial state for undo (spline-specific)
+	// Store initial state and show handles
 	if (IPS_Editor_SplineEditable* Spline = Cast<IPS_Editor_SplineEditable>(ExistingActor))
 	{
 		AppendInitialPoints = Spline->GetAllPointLocations();
 		Spline->SetHandlesVisible(true);
 	}
+	else if (bIsChildMovable)
+	{
+		AppendInitialPoints = IPS_Editor_ChildMovable::Execute_GetAllChildLocations(ExistingActor);
+		IPS_Editor_ChildMovable::Execute_SetChildHandlesVisible(ExistingActor, true);
+	}
 
-	UE_LOG(LogTemp, Log, TEXT("PS_Editor: Appending points to %s"), *ExistingActor->GetName());
+	UE_LOG(LogTemp, Log, TEXT("PS_Editor: Editing sub-elements of %s"), *ExistingActor->GetName());
 }
 
 void APS_Editor_PlayerController::FinishPointPlacement()
@@ -332,6 +345,11 @@ void APS_Editor_PlayerController::FinishPointPlacement()
 		Spline->SetHandlesVisible(false);
 		Spline->ClearHandleHighlight();
 	}
+	else if (PlacementActor && PlacementActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+	{
+		IPS_Editor_ChildMovable::Execute_SetChildHandlesVisible(PlacementActor, false);
+		IPS_Editor_ChildMovable::Execute_ClearChildHighlight(PlacementActor);
+	}
 
 	if (PlacementActor && SelectionManager)
 	{
@@ -452,6 +470,9 @@ void APS_Editor_PlayerController::DisableSublevelPostProcessMaterials()
 	ULevel* Level = CurrentSublevel->GetLoadedLevel();
 	if (!Level) return;
 
+	// Force lighting/rendering resources to initialize properly for baked lightmaps
+	Level->InitializeRenderingResources();
+
 	APS_Editor_CameraStart* CameraStart = nullptr;
 
 	for (AActor* Actor : Level->Actors)

Unreal/Plugins/PS_Editor/Source/PS_Editor/Selection/PS_Editor_UndoManager.cpp

@@ -1,5 +1,6 @@
 #include "PS_Editor_UndoManager.h"
 #include "PS_Editor_SplineEditable.h"
+#include "PS_Editor_ChildMovable.h"
 #include "UObject/UnrealType.h"
 #include "Components/ActorComponent.h"
 
@@ -9,6 +10,10 @@ void FPS_Editor_SplinePointAction::Execute()
 	{
 		Spline->SetAllPointLocations(NewPoints);
 	}
+	else if (SplineActor.IsValid() && SplineActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+	{
+		IPS_Editor_ChildMovable::Execute_SetAllChildLocations(SplineActor.Get(), NewPoints);
+	}
 }
 
 void FPS_Editor_SplinePointAction::Undo()
@@ -17,6 +22,10 @@ void FPS_Editor_SplinePointAction::Undo()
 	{
 		Spline->SetAllPointLocations(OldPoints);
 	}
+	else if (SplineActor.IsValid() && SplineActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+	{
+		IPS_Editor_ChildMovable::Execute_SetAllChildLocations(SplineActor.Get(), OldPoints);
+	}
 }
 
 void FPS_Editor_PropertyAction::ApplyValue(const FString& ValueStr)

Unreal/Plugins/PS_Editor/Source/PS_Editor/Serialization/PS_Editor_SceneData.h

@@ -25,6 +25,10 @@ struct FPS_Editor_ActorData
 	/** Custom property values: key = "ComponentName.PropertyName", value = text-serialized value. */
 	UPROPERTY()
 	TMap<FString, FString> CustomProperties;
+
+	/** True if this actor is tagged as preload (briefing/placement phase). */
+	UPROPERTY()
+	bool bPreload = false;
 };
 
 /** Serialized data for a complete scene. */

Unreal/Plugins/PS_Editor/Source/PS_Editor/Serialization/PS_Editor_SceneLoader.cpp

@@ -2,6 +2,7 @@
 #include "PS_Editor_SceneData.h"
 #include "PS_Editor_EditableComponent.h"
 #include "PS_Editor_EditableInterface.h"
+#include "PS_Editor_ChildMovable.h"
 #include "PS_Editor_SpawnableComponent.h"
 #include "PS_Editor_SplineActor.h"
 #include "PS_Editor_SplineEditable.h"
@@ -12,7 +13,7 @@
 #include "UObject/UnrealType.h"
 #include "Components/ActorComponent.h"
 
-bool UPS_Editor_SceneLoader::LoadScene(const UObject* WorldContextObject, const FString& SceneName, TArray<AActor*>& OutActors, bool bStripEditorComponents)
+bool UPS_Editor_SceneLoader::LoadScene(const UObject* WorldContextObject, const FString& SceneName, TArray<AActor*>& OutActors, bool bStripEditorComponents, EPS_Editor_SceneLoadFilter Filter)
 {
 	OutActors.Empty();
 
@@ -44,7 +45,7 @@ bool UPS_Editor_SceneLoader::LoadScene(const UObject* WorldContextObject, const
 		return false;
 	}
 
-	if (!LoadSceneFromData(World, SceneData, OutActors))
+	if (!LoadSceneFromData(World, SceneData, OutActors, Filter))
 	{
 		return false;
 	}
@@ -87,7 +88,7 @@ bool UPS_Editor_SceneLoader::LoadScene(const UObject* WorldContextObject, const
 	return true;
 }
 
-bool UPS_Editor_SceneLoader::LoadSceneFromData(UWorld* World, const FPS_Editor_SceneData& SceneData, TArray<AActor*>& OutActors)
+bool UPS_Editor_SceneLoader::LoadSceneFromData(UWorld* World, const FPS_Editor_SceneData& SceneData, TArray<AActor*>& OutActors, EPS_Editor_SceneLoadFilter Filter)
 {
 	if (!World)
 	{
@@ -99,7 +100,7 @@ bool UPS_Editor_SceneLoader::LoadSceneFromData(UWorld* World, const FPS_Editor_S
 	bIsCurrentlyLoading = true;
 	for (const FPS_Editor_ActorData& ActorData : SceneData.Actors)
 	{
-		AActor* SpawnedActor = SpawnActorFromData(World, ActorData);
+		AActor* SpawnedActor = SpawnActorFromData(World, ActorData, Filter);
 		if (SpawnedActor)
 		{
 			OutActors.Add(SpawnedActor);
@@ -113,8 +114,12 @@ bool UPS_Editor_SceneLoader::LoadSceneFromData(UWorld* World, const FPS_Editor_S
 	return SpawnedCount > 0;
 }
 
-AActor* UPS_Editor_SceneLoader::SpawnActorFromData(UWorld* World, const FPS_Editor_ActorData& ActorData)
+AActor* UPS_Editor_SceneLoader::SpawnActorFromData(UWorld* World, const FPS_Editor_ActorData& ActorData, EPS_Editor_SceneLoadFilter Filter)
 {
+	// Apply preload filter
+	if (Filter == EPS_Editor_SceneLoadFilter::PreloadOnly && !ActorData.bPreload) return nullptr;
+	if (Filter == EPS_Editor_SceneLoadFilter::ExcludePreload && ActorData.bPreload) return nullptr;
+
 	// Load class (supports both Blueprint and C++ classes)
 	UClass* LoadedClass = LoadObject<UClass>(nullptr, *ActorData.ClassPath);
 	if (!LoadedClass)
@@ -156,6 +161,12 @@ AActor* UPS_Editor_SceneLoader::SpawnActorFromData(UWorld* World, const FPS_Edit
 		Spline->ImportFromCustomProperties(ActorData.CustomProperties);
 	}
 
+	// Import child movable data
+	if (SpawnedActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+	{
+		IPS_Editor_ChildMovable::Execute_ImportChildLocations(SpawnedActor, ActorData.CustomProperties);
+	}
+
 	// Notify the actor that all properties are ready
 	if (SpawnedActor->GetClass()->ImplementsInterface(UPS_Editor_EditableInterface::StaticClass()))
 	{
@@ -211,6 +222,7 @@ void UPS_Editor_SceneLoader::ApplyCustomProperties(AActor* Actor, const TMap<FSt
 }
 
 bool UPS_Editor_SceneLoader::bIsCurrentlyLoading = false;
+bool UPS_Editor_SceneLoader::bIsEditorModeActive = false;
 
 bool UPS_Editor_SceneLoader::IsLoadingFromScene(const AActor* Actor)
 {

Unreal/Plugins/PS_Editor/Source/PS_Editor/Serialization/PS_Editor_SceneLoader.h

@@ -5,6 +5,15 @@
 #include "Kismet/BlueprintFunctionLibrary.h"
 #include "PS_Editor_SceneLoader.generated.h"
 
+/** Filter for selective scene loading. */
+UENUM(BlueprintType)
+enum class EPS_Editor_SceneLoadFilter : uint8
+{
+	All,            /** Load all actors. */
+	PreloadOnly,    /** Load only actors tagged as preload (briefing/placement). */
+	ExcludePreload  /** Load all actors except those tagged as preload. */
+};
+
 /**
  * Standalone scene loader for PS_Editor.
  * Loads a JSON scene file and spawns all actors with their properties and spline data.
@@ -37,13 +46,15 @@ public:
 	 * @return                         True if the scene was loaded successfully.
 	 */
 	UFUNCTION(BlueprintCallable, Category = "PS Editor", meta = (WorldContext = "WorldContextObject"))
-	static bool LoadScene(const UObject* WorldContextObject, const FString& SceneName, TArray<AActor*>& OutActors, bool bStripEditorComponents = true);
+	static bool LoadScene(const UObject* WorldContextObject, const FString& SceneName, TArray<AActor*>& OutActors,
+		bool bStripEditorComponents = true, EPS_Editor_SceneLoadFilter Filter = EPS_Editor_SceneLoadFilter::All);
 
 	/**
 	 * Load scene from an already-parsed SceneData struct.
 	 * Useful if you want to parse the JSON yourself or modify data before spawning.
 	 */
-	static bool LoadSceneFromData(UWorld* World, const FPS_Editor_SceneData& SceneData, TArray<AActor*>& OutActors);
+	static bool LoadSceneFromData(UWorld* World, const FPS_Editor_SceneData& SceneData, TArray<AActor*>& OutActors,
+		EPS_Editor_SceneLoadFilter Filter = EPS_Editor_SceneLoadFilter::All);
 
 	/**
 	 * Get the directory where scenes are stored.
@@ -80,6 +91,13 @@ public:
 	/** Static flag: true while SceneLoader or SceneSerializer is spawning actors. */
 	static bool bIsCurrentlyLoading;
 
+	/** Static flag: true while the PS_Editor runtime editor is active. */
+	static bool bIsEditorModeActive;
+
+	/** Returns true if the PS_Editor runtime editor is currently active. Callable from any BP. */
+	UFUNCTION(BlueprintCallable, BlueprintPure, Category = "PS Editor")
+	static bool IsInEditorMode() { return bIsEditorModeActive; }
+
 	/**
 	 * Get all saved scenes for the current level.
 	 */
@@ -87,8 +105,8 @@ public:
 	static TArray<FString> GetSavedSceneNamesForCurrentLevel(const UObject* WorldContextObject);
 
 private:
-	/** Spawn a single actor from saved data and apply all properties. */
+	/** Spawn a single actor from saved data and apply all properties. Returns nullptr if filtered out. */
-	static AActor* SpawnActorFromData(UWorld* World, const FPS_Editor_ActorData& ActorData);
+	static AActor* SpawnActorFromData(UWorld* World, const FPS_Editor_ActorData& ActorData, EPS_Editor_SceneLoadFilter Filter);
 
 	/** Apply custom editable properties to a spawned actor. */
 	static void ApplyCustomProperties(AActor* Actor, const TMap<FString, FString>& CustomProperties);

Unreal/Plugins/PS_Editor/Source/PS_Editor/Serialization/PS_Editor_SceneSerializer.cpp

@@ -3,6 +3,8 @@
 #include "PS_Editor_SelectionManager.h"
 #include "PS_Editor_EditableComponent.h"
 #include "PS_Editor_EditableInterface.h"
+#include "PS_Editor_SpawnableComponent.h"
+#include "PS_Editor_ChildMovable.h"
 #include "PS_Editor_PlayerController.h"
 #include "PS_Editor_SceneLoader.h"
 #include "PS_Editor_SplineActor.h"
@@ -49,6 +51,12 @@ bool UPS_Editor_SceneSerializer::SaveScene(const FString& SceneName, UPS_Editor_
 		ActorData.Rotation = Actor->GetActorRotation();
 		ActorData.Scale = Actor->GetActorScale3D();
 
+		// Save preload tag
+		if (UPS_Editor_SpawnableComponent* SpawnComp = Actor->FindComponentByClass<UPS_Editor_SpawnableComponent>())
+		{
+			ActorData.bPreload = SpawnComp->bPreload;
+		}
+
 		// Export spline data
 		if (IPS_Editor_SplineEditable* Spline = Cast<IPS_Editor_SplineEditable>(Actor))
 		{
@@ -57,6 +65,12 @@ bool UPS_Editor_SceneSerializer::SaveScene(const FString& SceneName, UPS_Editor_
 				Spline->GetNumPoints(), *ActorData.ClassPath);
 		}
 
+		// Export child movable data
+		if (Actor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+		{
+			IPS_Editor_ChildMovable::Execute_ExportChildLocations(Actor, ActorData.CustomProperties);
+		}
+
 		// Export custom editable properties
 		if (UPS_Editor_EditableComponent* EditComp = Actor->FindComponentByClass<UPS_Editor_EditableComponent>())
 		{
@@ -171,6 +185,15 @@ bool UPS_Editor_SceneSerializer::LoadScene(const FString& SceneName, UPS_Editor_
 		AActor* SpawnedActor = SpawnManager->SpawnActorDirect(LoadedClass, ActorData.Location, ActorData.Rotation, ActorData.Scale);
 		if (SpawnedActor)
 		{
+			// Restore preload tag
+			if (ActorData.bPreload)
+			{
+				if (UPS_Editor_SpawnableComponent* SpawnComp = SpawnedActor->FindComponentByClass<UPS_Editor_SpawnableComponent>())
+				{
+					SpawnComp->bPreload = true;
+				}
+			}
+
 			// Import custom properties
 			if (ActorData.CustomProperties.Num() > 0)
 			{
@@ -222,6 +245,12 @@ bool UPS_Editor_SceneSerializer::LoadScene(const FString& SceneName, UPS_Editor_
 				Spline->ImportFromCustomProperties(ActorData.CustomProperties);
 			}
 
+			// Import child movable data
+			if (SpawnedActor->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+			{
+				IPS_Editor_ChildMovable::Execute_ImportChildLocations(SpawnedActor, ActorData.CustomProperties);
+			}
+
 			// Notify the actor that properties were loaded and we are in editor mode
 			if (SpawnedActor->GetClass()->ImplementsInterface(UPS_Editor_EditableInterface::StaticClass()))
 			{

Unreal/Plugins/PS_Editor/Source/PS_Editor/Spawn/PS_Editor_ChildMovable.h

@@ -0,0 +1,71 @@
+#pragma once
+
+#include "CoreMinimal.h"
+#include "UObject/Interface.h"
+#include "PS_Editor_ChildMovable.generated.h"
+
+UINTERFACE(BlueprintType, meta = (DisplayName = "PS Editor Child Movable"))
+class PS_EDITOR_API UPS_Editor_ChildMovable : public UInterface
+{
+	GENERATED_BODY()
+};
+
+/**
+ * Interface for actors containing sub-elements (child actors, components)
+ * that can be individually selected and moved in the PS_Editor runtime editor.
+ *
+ * Implement this in your Blueprint to enable per-child editing.
+ * The plugin handles selection, gizmo, undo, and serialization.
+ *
+ * Example: VR placement root with 10 movable placement spots.
+ */
+class PS_EDITOR_API IPS_Editor_ChildMovable
+{
+	GENERATED_BODY()
+
+public:
+	/** Number of movable sub-elements. */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	int32 GetMovableChildCount() const;
+
+	/** World location of the sub-element at the given index. */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	FVector GetChildLocation(int32 Index) const;
+
+	/** Move the sub-element at the given index to a new world position. */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	void MoveChild(int32 Index, const FVector& NewWorldPosition);
+
+	/** Return all sub-element positions (used for undo snapshots). */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	TArray<FVector> GetAllChildLocations() const;
+
+	/** Restore all sub-element positions (used for undo). */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	void SetAllChildLocations(const TArray<FVector>& Positions);
+
+	/** Index of the sub-element under the cursor ray (-1 if none).
+	 *  Implement with sphere-ray intersection or any hit detection that suits your visuals. */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	int32 GetChildIndexUnderCursor(const FVector& RayOrigin, const FVector& RayDirection) const;
+
+	/** Show or hide visual handles for the sub-elements. */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	void SetChildHandlesVisible(bool bVisible);
+
+	/** Highlight a specific sub-element (e.g. change handle color). */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	void HighlightChild(int32 Index);
+
+	/** Clear all sub-element highlights. */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	void ClearChildHighlight();
+
+	/** Export sub-element positions to the CustomProperties map for scene saving. */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	void ExportChildLocations(TMap<FString, FString>& OutProperties) const;
+
+	/** Import sub-element positions from the CustomProperties map on scene load. */
+	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "PS Editor|Child Movable")
+	void ImportChildLocations(const TMap<FString, FString>& Properties);
+};

Unreal/Plugins/PS_Editor/Source/PS_Editor/Spawn/PS_Editor_SpawnableComponent.h

@@ -47,4 +47,9 @@ public:
 	/** If true, scaling is always uniform on all axes. Dragging any single axis scales all three equally. */
 	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Spawnable")
 	bool bUniformScaleOnly = false;
+
+	/** If true, this actor belongs to the preload/briefing phase.
+	 *  Use scene loading filters to load only preload actors or exclude them. */
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Spawnable")
+	bool bPreload = false;
 };

Unreal/Plugins/PS_Editor/Source/PS_Editor/UI/Widgets/PS_Editor_MainWidget.cpp

@@ -10,6 +10,7 @@
 #include "PS_Editor_SpawnableComponent.h"
 #include "PS_Editor_SplineActor.h"
 #include "PS_Editor_SplineEditable.h"
+#include "PS_Editor_ChildMovable.h"
 #include "PS_Editor_Pawn.h"
 #include "PS_Editor_PointPlaceable.h"
 #include "Widgets/SBoxPanel.h"
@@ -222,6 +223,39 @@ TSharedRef<SWidget> UPS_Editor_MainWidget::RebuildWidget()
 						.ColorAndOpacity(FLinearColor(1.0f, 0.6f, 0.0f))
 					]
 				]
+			+ SHorizontalBox::Slot().AutoWidth().Padding(8.0f, 0.0f, 0.0f, 0.0f).VAlign(VAlign_Center)
+				[
+					SAssignNew(ChildEditButton, SButton)
+					.Visibility(EVisibility::Collapsed)
+					.OnClicked_Lambda([this]() -> FReply
+					{
+						if (APS_Editor_PlayerController* EditorPC = Cast<APS_Editor_PlayerController>(GetOwningPlayer()))
+						{
+							if (EditorPC->GetEditorMode() == EPS_Editor_EditorMode::SplinePlacement)
+							{
+								EditorPC->FinishPointPlacement();
+							}
+							else if (UPS_Editor_SelectionManager* SelMgr = SelectionManager.Get())
+							{
+								for (const TWeakObjectPtr<AActor>& Weak : SelMgr->GetSelectedActors())
+								{
+									if (Weak.IsValid() && Weak->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+									{
+										EditorPC->BeginPointPlacementAppend(Weak.Get());
+										break;
+									}
+								}
+							}
+						}
+						return FReply::Handled();
+					})
+					[
+						SNew(STextBlock)
+						.Text(FText::FromString(TEXT("Edit Children")))
+						.Font(FCoreStyle::GetDefaultFontStyle("Bold", 10))
+						.ColorAndOpacity(FLinearColor(0.3f, 0.8f, 1.0f))
+					]
+				]
 			+ SHorizontalBox::Slot().AutoWidth().Padding(8.0f, 0.0f, 0.0f, 0.0f).VAlign(VAlign_Center)
 				[
 					SAssignNew(SplineDeletePointButton, SButton)
@@ -831,6 +865,7 @@ TSharedRef<SWidget> UPS_Editor_MainWidget::BuildSceneButtons()
 						}
 
 						// Notify all spawned actors: leaving editor mode
+						UPS_Editor_SceneLoader::bIsEditorModeActive = false;
 						if (UPS_Editor_SpawnManager* PlaySM2 = EditorPC->GetSpawnManager())
 						{
 							PlaySM2->NotifyEditorModeChanged(false);
@@ -1425,8 +1460,9 @@ void UPS_Editor_MainWidget::RefreshPropertiesFromSelection()
 		}
 	}
 
-	// Determine if a spline is selected (for Edit button)
+	// Determine if a spline or child-movable is selected (for Edit buttons)
 	bool bSplineSelected = false;
+	bool bChildMovableSelected = false;
 	if (CurrentEditorMode == EPS_Editor_EditorMode::Normal && SM->IsAnythingSelected())
 	{
 		for (const TWeakObjectPtr<AActor>& Weak : SM->GetSelectedActors())
@@ -1436,6 +1472,11 @@ void UPS_Editor_MainWidget::RefreshPropertiesFromSelection()
 				bSplineSelected = true;
 				break;
 			}
+			if (Weak.IsValid() && Weak->GetClass()->ImplementsInterface(UPS_Editor_ChildMovable::StaticClass()))
+			{
+				bChildMovableSelected = true;
+				break;
+			}
 		}
 	}
 
@@ -1461,9 +1502,22 @@ void UPS_Editor_MainWidget::RefreshPropertiesFromSelection()
 			HelpBarText->SetColorAndOpacity(FLinearColor(1.0f, 0.6f, 0.0f));
 		}
 		if (SplineEditButton.IsValid()) SplineEditButton->SetVisibility(EVisibility::Collapsed);
+		if (ChildEditButton.IsValid()) ChildEditButton->SetVisibility(EVisibility::Collapsed);
 		if (SplineDeletePointButton.IsValid()) SplineDeletePointButton->SetVisibility(bPointSelected ? EVisibility::Visible : EVisibility::Collapsed);
 		if (SplineFinishButton.IsValid()) SplineFinishButton->SetVisibility(EVisibility::Visible);
 	}
+	else if (bChildMovableSelected)
+	{
+		if (HelpBarText.IsValid())
+		{
+			HelpBarText->SetText(FText::FromString(TEXT("Child-movable selected — click Edit Children to move sub-elements")));
+			HelpBarText->SetColorAndOpacity(FLinearColor(0.3f, 0.8f, 1.0f));
+		}
+		if (SplineEditButton.IsValid()) SplineEditButton->SetVisibility(EVisibility::Collapsed);
+		if (ChildEditButton.IsValid()) ChildEditButton->SetVisibility(EVisibility::Visible);
+		if (SplineDeletePointButton.IsValid()) SplineDeletePointButton->SetVisibility(EVisibility::Collapsed);
+		if (SplineFinishButton.IsValid()) SplineFinishButton->SetVisibility(EVisibility::Collapsed);
+	}
 	else if (bSplineSelected)
 	{
 		if (HelpBarText.IsValid())
@@ -1483,6 +1537,7 @@ void UPS_Editor_MainWidget::RefreshPropertiesFromSelection()
 			HelpBarText->SetColorAndOpacity(FLinearColor(0.6f, 0.6f, 0.6f));
 		}
 		if (SplineEditButton.IsValid()) SplineEditButton->SetVisibility(EVisibility::Collapsed);
+		if (ChildEditButton.IsValid()) ChildEditButton->SetVisibility(EVisibility::Collapsed);
 		if (SplineDeletePointButton.IsValid()) SplineDeletePointButton->SetVisibility(EVisibility::Collapsed);
 		if (SplineFinishButton.IsValid()) SplineFinishButton->SetVisibility(EVisibility::Collapsed);
 	}

Unreal/Plugins/PS_Editor/Source/PS_Editor/UI/Widgets/PS_Editor_MainWidget.h

@@ -113,6 +113,7 @@ private:
 	TSharedPtr<SWidget> SplineFinishButton;
 	TSharedPtr<SWidget> SplineEditButton;
 	TSharedPtr<SWidget> SplineDeletePointButton;
+	TSharedPtr<SWidget> ChildEditButton;
 
 	// Simulate button
 	TSharedPtr<STextBlock> SimulateButtonText;