IMO every Galaxy should have a Command Keshik (like the Wolves) and it should probably be a Supernova of some variety. It may attach ‘permanently’ to a Cluster by usually dragging that Cluster with it everywhere it goes, but they should be independent.
Front Line or Second line Clusters should all have Aerospace, Vehicles, and Elementals attached in some form or another. Maybe as Novas, maybe as pure forces… but there is no good reason to exclude them from front line forces. Now second line might have a bit more than mechs, but that’s a nature of defensive, Harrison, or second line forces. Plus we need Valkyrie and Zeta back fully because specialization!
Not to say each Galaxy can’t specialize themselves, but if we are fully integrated into the Inner Sphere we should adopt everything we can to make us stronger if possible.
EDIT: Detach Silveroot and Ourse Keshik from Alpha Galaxy for logistical purposes. Again they could ‘attach’ themselves to a Galaxy, but I’d prefer if the Galaxy have its own Command Keshik and they would just ‘combine/override’ them if they took direct control. They’re supposed to be the big picture commander: let your subordinates do their jobs and don’t micromanage unless you’re REALLY REALLY good at it.
Just my two cents.