create game objects tree id - may be used as scene persisting unique id (as long as long tree is not changed of course)

TreeId.cs

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

namespace GameObjectHelper
{
    public static class TreeId
    {
        public static string Get(Transform endOfTree)
        {
            var treeId = new List<string>();
            var t = endOfTree;
            while (t != null)
            {
                treeId.Add(t.GetSiblingIndex().ToString());
                t = t.parent;
            }

            treeId.Reverse();
            
            return String.Join("-", treeId);
        }
    }
}