The sister is such a pice of shit.
"oh but she definitively has a tragic back story which will totally explain her behavior"
I don't care
"charitable with the property that's not yours" It's her flat, the fact that her parents pay/payed for it doesn't really change that and parents paying for accommodation of their collage student child is normal and not something to lode over them, you bitch. " what if you loose scholarship over this" ??? WTH would she loose scholarship because of this, you are just making stuff up and aren't even trying to think of something believable.