Hmmm, I wonder if you could make a ramp up into the box that still had high sides? They would still need to jump out though…

I’m also wondering if you could get a very very large box with low sides, and set it up so that all the hay and bedding is all the way on the far side, so they would have to go all the way in to get to it?

I’ve seen ferret litter boxes on the interwebs with one side that has a relatively narrow but very low-cut gap but other sides high. I can’t imagine a bun choosing to forego the comfort of the inside high corners with that box. Maybe check it out?

My elderly bun, Rumball, was leaving more poop outside of box but still pretty reliable about peeing. Sometimes there were 4-5 poops where he’d been napping, like he wasnt really conscious of doing them. He was blind and arthritic but still managed jump in and out the box for pee and majority of poops. Some exercise is good for them, when arthritic…

Are you trying any supplements with her?

Personally, I’d go back to the original box if it was only some poop out of box your were dealing with then. Both rabbits could be “protesting” the change also…

If the rug got peed on, they are very likely to keep doing that, I’m afraid.

Hmmm, I wonder if you could make a ramp up into the box that still had high sides?

I put a “half-step” outside the box, using a wide paving brick. They can still get front paws on it getting out and it gave some traction for getting in and out.
That might be worth a try.

With the pooping, has they’re been new pet additions to your home? Or any changes to Mosby she might be reacting too and marking with poop?

You could put a towel on top of something impervious like a rubber mat. The towels can be washed. When our bun went into kidney failure he was peeing so much he lost his already imperfect litter training so we eventually trained him to pee on towels on our fortunately tile floor. He has partially recovered from the kidney failure but we find this about a convenient as a litterbox so we are just letting it stay this way. I do a load of soiled towels every 2 or 3 days instead of changing the litter. I find it is about a wash, so to speak.