Keep everything VERY clean. Make sure there is no rat poop or pee or rat poison in their reach. Is there anyway you could keep them confined at night (like in a large kennel or in your bedroom? It would help keep the buns away from rooms (like the kitchen) where rats are more likely to visit at night. Don’t leave any food or trash out (it will attract more rats) etc. Maybe leave out some (non poison) traps. I’m generally not a big fan of kill traps, but when it comes to me/my pet’s health vs a mouse or rat, I’m sorry, I’m going to pick me and my pets.
Keep rabbit food and hay in air tight containers. If you leave it open, throw it away. We have a mouse problem at our house, and I keep all food in safe containers, keep the room clean and block any holes in the wall or floor. (steel wool dish scrubbies are good, and then you can duct tape over it to prevent the buns from ripping it out)
Good luck!