My friend, I believe she might be waiting for your sisters visit to end too. Sounds like you've a leech problem. You would have to have a hard conversation and tell that your sister is staying longer than planned and you need her to move out asap. It's hard, no other go. Sugarcoat as much as you want for your comfort, she could still make it ugly. Be prepared for it and do it. Leeches are not good for us.