Hi,
Sorry he’s starting to act out with the girls, but I actually have been surprised he’s been as good as he has so far considering his inability to tolerate your other two. I guess two suggestions come to mind.
First, next time he goes for one of them and/or makes digs and protest poops, say No loudly and put him back in his house right away. I think that Puff shouldn’t feel punished when he attacks her, and he should know he’s not behaving well. If he is OK with them for an hour, pet them all and give each a tiny treat (raisins all around) and praise them. End their group sessions with that, so they all go back at the same time at the end of a mutually positive experience. Let them associate each other with getting rewarded. (Bonding experts – is that right?)

Second, even though they all seem to be playing together, adhere more strictly to a bonding plan. Now that we have the bonding thread it is easier to find the good advice for every stage and decide what to do next. You’re bonding Cotton (we know he’s not very interested in bonding ever) with two of them, and the girls to each other, so it’s going to take more effort and patience. I think it’s very promising since they have done so much better so far than the prior buns, but Cotton can’t go back to his attacking mode. Sounds like they are OK, but you’re working more on bonding them with you right now with their individual attention. Now that you are close to all three and they know your home, limit their time to a more structured bonding schedule. Like introducing swapped stuffed toys with their scents for each one to get used to, neutral territory, making the livingroom for everyone, not just Cotton, etc. Have you considered setting a litter pan on the floor at your side when you’re lying on the couch so you can plop a bun into it at the first sign of needing to go?

Don’t worry about inspection. Cleaning is fine, put bunnies in their houses; you already know the management is on your side due to the discrimination.

I just remembered: Spockie would sometimes dig and wiggle and nip me just because he was trying to say “Mom, I gotta go NOW!” If I didn’t get him to the nearest litter pan (often the other room) he’d have an accident on me, and that was my own fault. If I rushed him to his pan, he would be clearly relieved – in more ways than one.