[Editor Extension] - Menu Helper

Sorry if the title is a bit deceiving and doesn't entirely convey what I'm attempting to do. I wasn't entirely sure what would be best to call it.

What am I attempting to do?

Alright, so I have a Class Type called Menu, which inherits from BaseMenu (Not Important).

If I want to effectively edit a specific menu, I have to make sure that it's the only one enabled. This, is entirely a pain if I have multiple menus. So I thought, hey! This would be a great opportunity for an Editor Script!

What functionality does it need?

So essentially if a Menu's GameObject or it's children are selected, then I want it to be enabled.

Any GameObject that isn't selected should be disabled.

If no GameObjects of the Menu type are selected, then it should try and Find a GameManager in the Scene and get it's CurrentMenu (This is specified in the Inspector).

What have I tried so far?

I've tried a very inefficient method just for testing and trying to figure out the best way to go about it. But I feel as though a CustomEditor or at least in the way I'm using it isn't the best option.

 [CustomEditor(typeof(Menu))]
 public class MenuEditor : Editor
 {
     private Menu[] _menus;
 
     public override void OnInspectorGUI()
     {
         DrawDefaultInspector();
 
         RefreshMenus();
 
         foreach (var menu in _menus)
         {
             menu.gameObject.SetActive(false);
         }
 
         var myMenu = (Menu) target;
         if (myMenu)
         {
             myMenu.gameObject.SetActive(true);
         }
     }
 
     private void RefreshMenus()
     {
         _menus = Resources.FindObjectsOfTypeAll<Menu>();
     }
 }

I know the above code doesn't include all of my functionality, and that's because for what I want to do the CustomEditor isn't a very good options. It only runs when a GameObject of type Menu is selected or it's inspector is modified in some way.

Any help is appreciated, thanks!