As of right now, None offers two things to potential mergers: A temporary House for the membership, and a Province. Provinces are voting districts wherein all the members of a Province elect one of their number to the Parliament (not set up until we get more people, which would be about the time a RIA sized alliance joins us). For RIA, I would make the House permanent. This would permanently give RIA two government votes. One in Parliament and one in the Noble Council.
I also discussed with Ferrous some time ago the possiblity of creating Satellite Houses.
Essentially, this would be similar to the way Puerto Rico works in real life. The alliance would switch AA to None and would be granted the full range of rights and protections afforded to members of None, but would be allowed to maintain their own government/boards/whatever seperate from None as they so choose. The only (and I mean only) restriction on them is that they should confirm any large foreign policies with the None gov first as it would reflect on us as well. Domestic affairs would be given entirely over to the House gov. Ferrous wasn't much in faor of this, but, if RIA was interested in this or something similar, I could get him to make an exception (or simply overrule him).