I've always thought to expand the front-room cat tree since there are five adults and they like height.
I'm currently mingling a second one together with the original in this configuration. It'll be a monster!
The one on the right is the old one, now completely disassembled as we clean it up and re-cover the uprights which also serve as scratching posts.
Hobbes supervised, tested, and approved the assembly of the new sections.