Back when I was a retarted 18 year old getting married, I had to tell MY OWN MOTHER, that she couldn't come to the reception. That killed me, I was told by my future in-laws the DAY OF!!! They cornered me and told me that I would be disfellowshipped if I didn't comply, and told me how she "knew this day was coming since I was 6 years old". It was absolutely absurd. There was a big blow out meeting in the back room before we tied the knot, between my elders, my dad, my mom, and the "3rd party elders". See we got married at a hall that wasn't ours, so then the Service Overseer of that hall took it upon himself to ruin the whole day. Stating that he'd see to it that everyone in attendance at that reception would be disfellowshipped, my future in-laws also threatened to have the reception cancelled if she was going to attend. My elders, and my dad were fighting for my mother to be in attendance. All the elders that were talking to me said the same thing, "its your day, and if you want your mother there, its fine, we will just not talk to her". See my mom's whole side of the family has never been Dubs, and has ALWAYS hated them, forever. My wedding day pretty much sealed that fate forever. In the end, mom didn't come to the reception, and her whole side of the family, hated me for it, it caused major problems for a long time. I even got bitched out by my grandma and aunt for it.
The deciding factor of why my mom didn't come... My future wife, was asked, "Do you want Bluesbreaker's mom at the reception", she looked my mom right in the eyes and said, "No". I held that against her during our whole marriage, many times we would fight because of our wedding day. I refused to look at our wedding photos or buy any wedding pictures because of the trauma caused to me on that day. Its truly no surprise that 5 years later, I filed for divorce, we had a terrible marriage.
My advice, very simple, you go, and you go to both, and you tell that no it all elder, REALLY LOUDLY, IN FRONT OF EVERYONE, TO KISS YOUR ASS!!!