FaceMaps in Blender

Anyone notice you can’t save a face to more than one face map?

If I make a selection of faces and save to a facemap, if I create a new face map and add a new selection of faces and it contains one of those faces assigned to the first face map. The first facemap no longer contains those faces?

EDIT: If you are having this issue with face maps. Use Forgotten tools. works way better:

Its kinda wierd how there are so many awesome addons that do certain things Blender doesn’t do natively and many of us will never get to know about them. I kinda stumbled on this tbh.