How to scale grouped BSP / brushes relative to shape?

I have a basic square house structure with a floor and 4 walls. I’ve grouped these 5 brushes and am attempting to scale the entire structure down within the X-Y axes. Attempting to scale this group of brushes scales the objects relative to their own position, it looks like. I’ve done some searching around and see hints that the behavior I’m seeking is not possible unless converted to a Static Mesh. Is this true?

When converting to static mesh, subtractive brushes (for windows, doorways, etc.) disappear.

What is the best approach of scaling groups of brushes? Thank you.