Nice Work, There
When a family member is in need, people instinctively want to provide a helping hand. Having them stay with you for a short time is one option. When you’re staying at someone else’s house, whether or not you’re related to them, you must treat them with respect.
Because she’s plainly not, the two of them have been keeping a respectful distance from one another. Changing things around because you’re not content with them isn’t an option.