So everyone seems to be adjusting well. We still separate them when we aren't home and when we go to bed just to be safe but for most of the time we are home they are together.
They spend a lot of time snuggling and grooming each other. Occasionally we hear a little squawk from Stoli (that's what we've named the new one) but I think it's because Maggie isn't quite so skilled at her grooming technique and tends to get a little closer to Stoli's ear then Stoli would prefer.
So far though no fighting, biting, kicking or bickering at all. I'm actually very relieved, everyone said there would be the most chance of fighting between two females but they appear to enjoy each others company.