The more buns in the mix, the more personality comparability matters so something you’ll need to accept is the chance that these four will not work as a quad and having 2 bonded pairs may be a fine compromise, or a trio and a single (if one of the rabbits does not seem particularly keen on bonding, which some rabbits do do fine as singles with proper engagement from the owner). Depending on which you think would be more agreeable, I’d start there rather than throwing all 4 in the mix, especially if it’s weakening the preexisting bond.

It is actually not unusual for larger spaces to seemingly create harmony — it tends to be because the rabbits can stay out of each other’s business; however, this means they aren’t communicating and working out their dynamics, so the interactions are important, including the more tense ones. Large space harmonies can go awry quickly as exploration begins into other’s areas. We always intervene when there’s a fight, however, in some cases, short chases, nips, etc. are a part of the communication that needs to happen during the bonding process and large spaces sometimes won’t facilitate that.

If there is so much aggression across pens, I think you need to slow down. You are mentioning you want this done asap, and also rushing bonding almost never goes well… I understand wanting things to be streamlined though. Unfortunately, rabbit bonding, especially a quad, follows its own schedule; not ours. So frustrating!

I’ll add that the scent of other rabbits can facilitate aggression, so if you decide to just work on the other pair, be mindful of what you and your clothes smell like. You could be introducing dynamics you don’t intend to.

So, I only have experience with a failed quad, LOL, but here are my thoughts.

I completely understand the desire to get them bonded to make things simpler (and also improve the buns lives, because they would presumably get more exercise time and space). But, in my experience, putting pressure on you (and them), to be bonded as quickly as possible can make things really stressful and harder over all. Especially in a case where a bun is easily stressed or injury prone, it’s important to go at their pace. Bonding is very stressful for rabbits, and if one rabbit is having a health issue it can create a false hierarchy that falls apart later.

There are a few ways to go about things. While eventually you do need to work with all 4, it can be practically easier to at least get the pairs acquainted with each other first (so you don’t end up with immediate 4-bunny fights in sessions). A lot of it has to do with the bunnies and what you feel comfortable doing. I don’t think it makes sense to go for the trio and then the quad though. I would either get the other pair bonded and then add the two pairs together, or just work with all 4 at once. This could still mean working with all the different combos of 2 individually, because you might find that 2 of the bunnies are having the most issues.

I think it makes a lot of sense to start with the two un-bonded buns first. But, once you start working with the quad in earnest, their bond might break, as could the other pair.

Would having 2 pairs be an option for you if the quad doesn’t work out? That’s what I ended up with when my quad wasn’t working, and the buns are all very happy with the arrangement.

I agree that the fighting through the bars is not great. You mentioned you’ve had them a long time, but have you done side swaps or other forms of “pre-bonding”? Buns often will get along just fine with a neighbor until they realize that neighbor might be trying to invade their turf. It may help your pair to calm down if you add a visual barrier to block the other buns, like a towel hung over the pen wall. You can try this with your solo boys too while they calm down. They will still be able to smell each other but won’t be able to harass each other through the fence.

When I tried to bond my quad the boys were giving me the most trouble and were ultimately why I called it off after about 4 days of marathon bonding, so you definitely have a challenge ahead. Given Sage’s health issues, I agree that going with 24/7 bonding right off the bat is not a great strategy. You don’t want to end up in a situation where she’s getting along with them, but it’s just because she’s scared and stressed, and then down the road you have issues. I think it would help to do pre-bonding with all the buns, and then start with shorter sessions with each combo to get a sense of how they get along with each other.

There are a lot of bonding journals here that use a variety of methods. If you search the forum for “trio bonding” or “quad bonding”, you will find some threads that might help you as well.

That sounds like a good decision based on the situation! I really enjoy having two pairs, and it’s great you are making progress with the new pair! They look great together!

That sounds really positive! They are definitely making progress!

If you’re referring to the cage area that’s the bonding area, yes I usually clean the area in between so all the hay is fresh and the area smells more neutral. Plus once the sessions start getting longer the area will definitely need cleaning. :p