I am having a destination long weekend for a bachelorette. I am inviting my bridesmaids and a few close friends. I don't want it to be too many people since we have to think about hotels and whatnot. My question is, do I have to invite my fiancé's sisters? One of them I talk to frequently, the other, we never talk. I figured it has to be both or none. What is the proper etiquette? They are not bridesmaids, but may do a reading or something at the wedding. Thoughts?