My sunny bunny, Hazel, had a week or so of cage aggression when she was about 11-12 weeks. I was seriously getting anxiety every time I reached in to restock her hay, pellets, and clean her litter pan. She then stopped at about 13 weeks, and we got her spayed at 15 weeks. She’ll be 18 weeks soon, recovering well, and is quite a docile bunny. She can get a little skittish at times, but mainly in the morning before we let her out for play ~ at that time she doesn’t want to be bothered....she just wants to get her wiggles out.
Does your bun have any out-of-cage time at all, even if in a small fenced off, dog-free area in the yard? Aside from spaying, that could help with cage aggression.
As for litter training, do you place a litter pan in your outdoor cage? If so, it’s best to keep the rest of the cage floor free of “bedding” because if she doesn’t currently have a litter pan, then she views her whole cage as her “litter pan”
Our first bunny had a hard time with litter training, and that was my fault. She did have a litter pan in her outdoor bunny condo, but when we first brought her home, I didn’t confine her to her new environment for 36 hours. She had an outdoor condo on our lanai where she slept at night, and then she had a small indoor playpen downstairs for daytime. Both had litter pans. She did use both of them, but still had many droppings outside of the pan, and still peed on the outside of the pan when she was moody. This is probably because she had to get used to two separate environments, not to mention, our cat often jumped into her indoor playpen, so she had to place her “territorial drippings” throughout the perimeter of the playpen. This drove me nuts. But I understand why she had to do it.
So as you can imagine, your situation with mature indoor dogs, and now bringing a bunny into the situation....there could be some challenges, but with a little strategic planning, it’s not impossible to overcome. I know someone who already had a big dog, and then brought home a baby Lop bunny for indoors. They’re best buddies now. So you might have to get each dog used to the bunny one on one before bringing all three in with her, especially since right now she associates all their barks at her as aggressive. It could be stressful for her. But again, I’m sure some creative and strategic planning for her indoor space, as well as spaying, recovery, and her bonding with you, and then eventually one dog at a time could help.
. i was just wondering the steps to getting them to like each other. thanks 
