We've bonded three rabbits and have had a problem with getting them litter trained since. It's getting better and there are fewer wees and poos on the floor. However, I'm noticing that one of the bunnies, even with her best attempts, end up peeing on the floor because she places her butt over the edge of the litter box. The size of the litter box isn't the problem. All three can fit in there if they wish. But she literally places her butt over the edge so it all ends up on the floor anyway. We use cat litter boxes and we have three of them. We don't have any shops available here so any solution in terms of getting a different type of box isn't helpful in the short term.