Okay, before I went and tried to combine Mimzy and Pip’s cages about two or three weeks ago (?) the two bunnies were getting along in a champion fashion. I was sure they were ready to share one dwelling. (They’d been going through the bonding process for a few months.)
I was used to seeing Mimzy doing his best to let Pip know who was boss. I admit, I would break it up if he mounted her face, as I didn’t want to see him get bitten, but for the most part, there wasn’t much of that and they settled down almost immediately to a grooming and cuddling routine.
When the combined cage system didn’t work, I replaced Pip’s cage on top of Mimzy’s (the only way they fit in that room) and thought, well, we’ll start over. Now I am beginning to think that, since Pip has been living in my room with Mimzy and I, and she must know she has ‘the Penthouse’, maybe she is thinking she is the boss bun?
Now, it is Pip who does the facial mounting when they are together, and she tends to nip him on the bum or flank quite often. So far, I am lucky she hasn’t broken skin, but I am afraid it is just a matter of time. Should I then halt the bonding process and just resign myself to the idea that they are not going to get along? Or is this just one step in the whole dance? They still groom each other, although Mimzy presents much more often than Pip and she simply won’t comply anymore.
I still see them grooming…it just doesn’t have that real cozy feel it used to. 
What should I do?
P.S. Oh, and one other thing. But I kind of doubt it holds any water. During this time I got another Binky Box. It had been full of hays and mats and so on, and it was such a nice box, I decided to add it to the xpen as a plaything. Pip immediately claimed it for her own and soundly thumped whenever Mimzy tried to go in there (not that this stopped him). There was finally so much thumping going on, and a bit of chasing, that I decided to remove the box. Is it possible that they scented the other bunnies (Jennifer’s) and this may have set off the territorial thing again? I don’t know if BB packs the boxes in her apartment or if they are put together elsewhere, but I wonder why this box made Pip so angry and yet the others I’ve gotten from Binky didn’t seem to. It was just kind of weird.