Hi Darwin, I am certainly no expert, but I can share my trio bonding experience with you. I hope your buns are doing well? I hope you haven’t given up, because having a trio is super rewarding in my experience.
I had a bonded male female pair for a year when I got another male from a friend who didn’t want him anymore. I kept him in a large cage in the other buns’ space for a week and the same thing happened as with you. My bonded pair was going nuts, pooping and marking all around the cage, trying to scratch and bite him through the bars. Luckily the bars were close enough together so they couldn’t harm him. They even started chasing each other around and it looked like their own bond might be breaking because of the confusion of another bun in their territory, and I was very worried and sad, obviously.
But I kept his cage in their territory and their craziness gradually calmed down, day by day. I read somewhere about a lady who bonded her buns on her dining room table, so I decided to try that as I didn’t fancy putting them all three in the bathtub and I don’t own an xpen. The theory is that it’s high enough for them not to attempt to jump off and obviously neutral territory, so that and the unsure footing also puts them off guard. I never ever did this by myself, though, I would suggest you get a friend to help you ward them away from the sides, because my male did look about to jump a few times and that could cause serious injury.
I never did single sessions, fearing the breaking of my bonded pair’s bond. We kept towels ready to stick in front of them in case of lunging or fighting, which worked really well. I put a litterbox with hay on the table, with food on one end of the table and water at the other, making sure there were no corners for a bun to get trapped in. The table was against a wall, so I felt like my friend and I could control the remaining three sides well enough. You could try an xpen in a neutral room? We started with 15 minutes a day, if there was a boring day, we’d make it longer and end off the session with a treat. My buns love grapes or raisons, so a half a grape each at the end of the session, then back to their areas. I would be happy with sessions where they just sit and do nothing, if I were you. Give them time to get used to each other just being there, trust me it’s a good sign! Eventually I made the sessions 1 hour each, one session per day. If there was more chasing than usual, I’d cut the session short, but still give the treat at the end. I noticed that if they were chasey, it helped if I spoke or sang to them soothingly while gently stroking all three of them together. I’ve gotten really good at stroking three buns at the same time. Some people say not to touch them at all during bonding, but it helped in my case. Also, try to do the bonding in the middle of the day, when they’re not in full play mode.
After about two weeks of this, I did a session with them on the bathroom floor, there was more chasing than normal, so I did a few more sessions on the table until they weren’t chasing at all anymore and there was a lot more snuggling, flops and grooming. I decided the bathroom wasn’t the greatest choice for my bonding because it was cold and my new bun had just recovered from snuffles, so I kept them in the kitchen for a day and a night, me sleeping on the floor with them. There were no more chasing so I opened the lounge to them. They chased a little bit, but I think they were just excited at being allowed in the lounge again for the first time in so long. After they tired themselves out exploring the lounge, they snuggled together and they’ve been bonded ever since.