FI has 2 young half sisters, 12 and 14 (his mom's daughters) he is not close to them at all. FI would rather invite another close couple instead of his sisters. I guess you can say we are having a 18+ wedding, but they are family. I just think it's so rude, but I do see his point. They are young, they probably won't have much fun and he isn't at all close to them.
So how awful is this? Have you been in a situation like this?