Custom Unity Editor Script to Fix [SelectionBase] for Consistent Parent Selection

FixUnityBrokenSelectionBase.cs

using System.Collections.Generic;
using UnityEditor;
using UnityEngine;

// Put this in an Editor folder
[InitializeOnLoad]
public class FixUnityBrokenSelectionBase : Editor {
    static List<Object> newSelection;
    static Object[] lastSelection = { };

    static FixUnityBrokenSelectionBase() {
        // Subscribe to selection changed events
        Selection.selectionChanged += OnSelectionChanged;
        // Use update event to modify selections after changes
        EditorApplication.update += OnSceneUpdate;
    }

    static void OnSelectionChanged() {
        // Check if the mouse is over the SceneView
        var editorWindow = EditorWindow.mouseOverWindow;
        if (editorWindow == null) return;

        // Only modify user selection if selected from the SceneView
        if (editorWindow.GetType() != typeof(SceneView)) return;

        // Look through the current selection
        var futureSelection = new List<Object>();
        var changed = false;

        foreach (var go in Selection.GetFiltered<GameObject>(SelectionMode.Unfiltered)) {
            changed |= AdjustIfNeeded(go, futureSelection);
        }

        // If nothing has changed, set the future selection to null
        if (!changed) {
            futureSelection = null;
        }

        // Atomically update newSelection
        newSelection = futureSelection;

        // Remember this selection to compare with the next selection
        lastSelection = Selection.objects;
    }

    static bool AdjustIfNeeded(GameObject go, List<Object> futureSelection) {
        var parentWithGlobalSelectionBase = ParentWithGlobalSelectionBase(go);
        if (parentWithGlobalSelectionBase != null) {
            // Replace selection with GlobalSelectionBase parent
            futureSelection.Add(parentWithGlobalSelectionBase.gameObject);
            // Debug.Log("Selecting parent: " + parentWithGlobalSelectionBase.name);
            return true;
        }

        // Add the original GameObject
        futureSelection.Add(go);
        // Debug.Log("Selecting original object: " + go.name);
        return false;
    }

    static void OnSceneUpdate() {
        if (newSelection != null) {
            Selection.objects = newSelection.ToArray();
            newSelection = null;
        }
    }

    static GameObject ParentWithGlobalSelectionBase(GameObject go) {
        if (go.transform.parent == null) return null;

        foreach (MonoBehaviour component in go.transform.parent.GetComponentsInParent<MonoBehaviour>(false)) {
            if (component.GetType().GetCustomAttributes(typeof(SelectionBaseFixed), true).Length > 0) {
                return component.gameObject;
            }
        }

        return null;
    }
}

SelectionBaseFixed.cs

using System;

[AttributeUsage(AttributeTargets.Class)]
public class SelectionBaseFixed : Attribute { }