This is a losing battle. If she's elderly with mental impairment, you will not be able to reason with her on this subject. In private, you can explain the legal
and financial consequences of saying the wrong thing, and it might sink in, but as she loses control of her mental faculties, it will most likely come out anyway. The workers will not like it, and certainly a roommate will not. In some cases, she will be asked to move out of the facility. The other choice will be to drug her senseless so she won't say the wrong thing. If you are lucky, you will find a facility where the workers actually have some experience with the elderly and can put their egos aside and deal with the patient properly, as they are supposed to do anyway. Nothing she says should change their care of her, but it usually will. All you can do is to relax and let her take her lumps as they come. You are not responsible for what she says or does. You will surely drive yourself crazy trying to keep her in control.