Can I leave one of FI's sisters out of my bridal party?

Hello WW! Long-time lurker, first-time poster. Need help with this: FI has 3 sisters & we get along fine, with the exception of one sister who I'll call Amy. One of the first things she said to me was that I was "chunky." Didn't think much of it since I could stand to lose a few pounds. But the entire time FI and I were dating, she kept trying to hook him up with one of her friends who really liked him. Amy even brought this girl as an uninvited guest to a surprise birthday dinner I planned for FI, & the girl ended up sitting directly across from FI & I the entire night, watching us & listening to our conversations. AWKWARD. After we got engaged, Amy was the only person in FI's family who wasn't happy for us. FI asked me to put his sisters in my bridal party. Definitely don't wanna include Amy but think it's wrong to include the others & not her. I'm not close with any of his sisters so I could exclude them all, but I want to honor FI's wishes to involve his sisters. What should I do?