Our wedding is September 26, 2014 at the Moon Palace in Cancun. My FI's original best man was also his sisters fiancé. However, she stopped talking to him in January and has called off their engagement. We now have a new BM and her ex isn't coming.
Now the dilemma, our prices are based on double occupancy and include flight and air tickets. His sister refuses to stay in a room with his mom and I told her a single room is more expensive. She says to me "Well can't I just lie and say someones there?" I told her why she couldn't do that and she says "Well I will just find someone to come and figure it out". She's not in a serious relationship with anyone so we haven't included a "plus one" for her. She's crazy and not a nice person so I don't want to chance her bringing a random fling or a friend we don't want there. It's a tough situation so I'm torn whether to suck it up and let her bring someone or just tell her she can ask a family member who would like to go to room with her.
Any advice since it is a destination wedding and not your typical wedding? Should I follow the same "plus-one" etiquette?