Hi.
You didn’t include any information on their housing or other important information.

Are they spayed and neutered? Are they housed together? Are they bonded? Did you do any litter training? There are many forums and articles on it but the basics is that you put them in a small area with the litter box, slowly increase the space when they use it and decrease it if they don’t.

You said in a previous thread you just introduced a new third bunny into your home that isn’t neutered yet, A member had said on that thread, and I will reiterate it, that they are marking. Although your pair may be bonded and fixed, they can still act on the hormones of an unfixed bunny. They aren’t going to get any better until the third bunny is fixed and all three are bonded. Until then it’s honestly going to be poop city and even pee city if one of them likes to mark with urine.

To make things easier and lay a foundation for when they are all bonded, don’t just stick a litter pan in their space and call it a day. You actually do have to train them somewhat. Put their hay in the litter box so they’re more inclined to go in and use it. Put a layer of compressed pine pellets on the bottom and load up the hay on top, and odds are they will go in. Most bunnies do their business while they eat, so this encourages them. If you see one of them about to pee outside the box you can gently nudge them to the box.

But honestly you and your mom are going to need to just have patience with the poop until all of them are bonded.