AFAIK, faction adoptions exist. I did this with the Baroka (albeit, they were flagged for deletion and aren't intended to be more than an NPC/minor faction). I think it may be best to ask here and see if anyone has issues, along with more formally show your intentions while asking Wes.
It's better to grab old factions rather than make new ones, after all.
Edit: I think a Faction WIP could be, but it likely follows similar rules such as ensuring the content was ALLOWED to be adopted.