Here is a script that you can run in the editor console, and automatically assign a material to a mesh instance slot on several model assets at the same time.
You can rework it a bit to do something similar for your use case to assign the same material in multiple mesh slots:
Cool! I missed the feature. That part of the problem is solved then, I assume that if a mesh as 2-3 materials, I just use the replace feature on each of them?
So what about the mesh instance customization part?
My understanding is that the replace feature would work replacing the asset materials right? anywhere its used? Which is nice now that I know about it.
What about the entity materials? To customize the entity, I need to select all submesh materials I want to replace one by one. ref: original post image
Only one in that specific case. But maybe I would like to change a few petals color. Or maybe I could have a complex car model in the futur that have many parts.