My fiancé and I are currently not speaking to his sister for a multitude of reasons. We know that for etiquettes sake we need to invite her and we are fine with that. Our problem is that her ex is one of our closest friends to the extent that we want him as a groomsman, and my fiancé's sister has been known to create a scene and has in the past created many difficulties for our friend. Because of the distinct probability of drama, he is hesitant about even comeing to the wedding none the less be a groomsman. I feel like I'm stuck between a rock and a hard place, etiquette demands that I invite her yet the wedding won't be as meaningful without him.