I had it happen to one of my five kids. The first child was in scouts as a child and nothing as a teen and didn't go to a grad. my second was in no activities and was called to grad, and her entire family was forced to go (they all got an automatic call and dropped what they were doing) the last three (triplets) two had after school activities, third didn't and none got called to grad. Only thing different was they day they grew up on (though it shouldn't really matter) and the one who went to grad grew up on a Friday, grad was on a Saturday. the others grew up mid week.
Don't know if it helps, there was no opportunity, it just happened and the whole family went.