Here is a screenshot of the parent blueprint: as you can see in the top left, I have created a skeletal and a static mesh.
I need a “set collision response to channel” for each type of object (in the switch). Now I can do it because I have both the meshes that will be used for one or another child blueprint (since some use static and some skeletal). I don’t know if this will bring me any problem later on.
Then in each child blueprint I select the type of mesh that fits the object’s mesh (skeletal or static) and I set the other to no collision and to not tick.
The other option would be to go to number 2 of the original post.