Hi @Star14,   Sounds like a really tricky situation and I can see why you are struggling.  When  you and your partner have had a chance to talk things through, it might be worth you both agreeing on some ground rules that you and he would be happy with.  When you are agreed, maybe you could sit down with his sister and explain that while you are pleased to have her staying with you, she needs to understand that every house needs to have some order.  Take the time to make sure she knows she is welcome and loved and that you are there for her, but every relationship, whatever dynamic it is, has to have some give and take.   During the discussion, you could ask her for her thoughts on what she thinks would be acceptable while she is staying with you and make sure that you listen to her views as well.  Hopefully, together you will be able to reach a point where the arrangement works for you all.   Keep us posted and really hoping that everything works out for you. Take care xx ... View more