In the release notes for 5.6.256
https://github.com/4ian/GDevelop/releases/tag/v5.6.256
Allow to override behavior properties on object instances: for now, this is limited to instances inside custom objects. This will be made available in the future for all instances in scenes if this works well.
Does anyone know more about this?
Edit: I think I solved this. If you check the instance properties of a child object in a prefab, you can change the behavior properties on an instance level.
That is great news! I have secretly wanted this for a while. So this means we can define properties per instance in the visual editor without requiring event picking logic, right?
That will make hand placed level design so much more convienient - nice! 
Currently just for the children of custom objects but it’s a start.
I had this feature last year, and it was available for all objects.
Do you still have it for all objects? On the mobile version, I only see it for the children of custom objects.
