So i'm on Blender 3.1

-> My solution is to create a string property on my special collections. -> Loop into all collection of the scene searching for the property and value

-> the value is an encoded key, so the user is not suppose to touch it but he can change the name of the object / collection / special item.

-> I have lot's of collections in my tools, but I'm make sure that I clean the unused ones and store data into json ( to be able to call them back if needed)

In Blender 3.1, my solution is to create a string property on my special collections.

1. Loop into all collection of the scene searching for the Property and Value

2. The Value is an encoded key, so the user is not suppose to touch it but he can change the name of the object / collection / special item.

I have lot's of collections in my tools, but I'm make sure that I clean the unused ones and store data into json (to be able to call them back if needed).