My mother-in-law insists on adding people the the guest list, and wants her friends to bring uninvited guests. We are only allowed to have 75 people or less at the venue before they charge us a ton more money. We are paying for the entire wedding, so we want a small wedding. I don't want a ton of people I don't know. In fact, I don't want any people that I don't know. How can I kindly tell my mother-in-law that the guest list is set? And How can I nicely let people know that they are not allowed to bring all of their friends? Help!