Nah, I don't agree here. Drawing this as 3 buildings means it can't be imported from GRB to have the precise geometry, because it's present there as one building. It's also not 3 separate buildings, it's one building with distinct parts.

I really don't see why `building:part=*` can't be used here. If there's no objections, I'll import this building from GRB, then draw 3 shapes and tag them with `building:part=*` and `name=*`.