Passive-aggressive
I interpret that meaning that you are afraid to define your boundaries and someone is stepping past yours. So you deal with it behind the scenes.
Sometimes that is good, when the person stepping over is physically dangerous.
The best thing to do is find a quiet moment, lola, and talk to your sisters. I assume that they are not young children. They must respect your possessions, especially if you are paying out of your pocket and it is not the family shampoo bottle.
It is matter of being afraid to confront the person, that the either will not like you or could be dangerous as misspeaches roommate's boyfriend sounds to me.
A friend told me about a recurring dream she had:
An alligator followed her around the house trying to bite her. She kept trying to get up on furniture, leave the room and shut the door, but the alligator always got past those barriers. Finally one night after weeks of sleepless nights, she decided to let the alligator bite her. Well, of course, she felt nothing and promptly woke up and never had the dream again.
The point, when she confronted her fear, it was easier to deal with.
Not quite up to Christ's standards but it meant something to me.
Some situations we can't confront right then, too dangerous, but it can change.
Other situations we can confront, but avoid and they get worse and worse.
You have to decide what is safe.
Love, Blondie (a recovering P-A personality)