Not sure how it works in your state but both parents have to have "space" for the kids when they visit. I would think that a 2 bedroom would be a requirement for her to have the kids overnight. I know you dont want her to be able to do that anymore so maybe you'd just be happier if she stayed in the 1 bedroom and didnt have a place for them. Just throwing it out there because if she asks for more I believe she would have to have more space for them.