No, that's really not cool, at all. I get that they changed their mind about their wedding, but so close to the wedding, when they should know that people have already bought tickets and aren't refundable, I'm not saying have the wedding, but at least maybe a reception to say to the people who did bother to make an effort, thank you?

Just really inconsiderate. I hope your sister and BiL have a wonderful time there, regardless.

*shakes head* Some people, I swear.