Hey BF, My D doesn't want them to be there. She will be hurt and also mortified in front of all her school friends, their parents and her teachers who have known us as a family all of her life, just about.
We thought of ringing XH and asking him not to come, but in the past, this has simply strengthened his resolve. He will NOT be told what to do by us... He has no control over what OW does... and similar dumb-arse comments. He always makes it very clear that he values OW above us whenever the occasion arises.
At the moment, we don't know for sure that he is aware of the event tonight - so we don't really want to bring it to his attention.
But the chances are that he does know - and, if past performance is any indication, he will show up with the hag.