Two of my sister's friends came by yesterday. At different times. One was unexpected and came later. He showed up walked in like he owned the place. Ugh. He said to me, "Oh so you're wearing something different for once." He didn't say it in a nice way. I think it was rude. I can't imagine going into someone else's home and saying something like that. It's not the first time he's sad things in general that are rude, inappropriate or making "adult" remarks that aren't funny. He is very obnoxious and I can't stand him. I can't ask him to leave because my sister lives here too. I wish I could. My sister let him and her other friend eat dinner here. I didn't enjoy that. If I could I would make boundaries and rules. Common decency isn't asking too much.

Since you are letting your sister live in YOUR house, not hers, you have the right to say what visitors are allowed. Like children who live in their parents' house, the parents have the right to say someone can't visit. You had mentioned before that your sister doesn't pay rent, if that is still the case she should defer to what you want. Also, you could always kick out your sister as you haven't really wanted her there in the first place. Don't worry about what your family would say as it sounds like they have treated you like crap and walked all over you. If necessary you could always change your locks and get the police involved if your sister refuses to leave. She is a grown woman who should not have to be your responsibility.

I agree with catsule. You're completely within your rights to set the rules. At the very least I would be transparent with your sister and let her know how her friends are making you feel.

It's inexcusable for anyone to say/do that to you where you live. As I said in another thread...

If your sister is living with you rent free I would make it so miserable that she would want to leave. She better have a mop or a broom in-hand at all times. She'll be living in a room like Harry Potter under the staircase.

She'll be waiting on you 24/7: meals all prepared, making the bed, laundry, kitchen/bathroom scrubbed, garden (if you have one) mowed, all the shopping... everything regarding the household she'll have to do. TV, Internet, Phone (any rec time) will have to be earned, no relaxing allowed.