Add a new rule, Respect:

All Shifters have a Respect score, which is an integer equal to their Cover minus their Form’s Reputation.

Any Shifter may attempt to Merge factions by sending a private message to the Forest stating this intention, and stating a Base faction and a Merging faction. At the next New Day the Merge message coming from the Shifter with the highest Respect takes effect. Any Shifter who would become aligned with the Merging faction instead becomes aligned with the Base faction.