Do they normally go in the litterpan? If not you could try to litterpan train them - put some hay/newspaper in a litterpan (maybe one that kinda resembles the house) with a bit of pee and poop. And then clean the house with white vinegar so they can't smell the pee scent that will encourage them to keep going in it. Sometimes it can be hard to get them to stop if they really like to pee in it though.