Having another woman live with you can be a problem. I trust my sister and most would not do anything. Your husband on the other hand sounds like he is crossing the line. Your sister might be uncomfortable to ask him to stop or she might feel rude to tell him not to touch her. If it were me. I would talk to my sister and ask her not to let my husband rub her down all the time. My sister would understand and I'm sure yours will too. Sounds like your husband is having a "sister" sex fantasy that he needs to get out of his head. You should also have a talk with your husband and tell him to keep his hands to himself.