When I was directing THE MAN WHO CAME TO DINNER - I had a small group of boys who played the choir that came in at the end of Act Two.
One night after rehearsal, one of the boys raised his hand and said, "My mom told me to tell you that I won't be able to be in the show, we are going on vacation."
I said: "Well then, you don't have to come to any more rehearsals."
He said: "Oh I can come to all of the rehearsals, I just can't be in the show."
I said: "Have you mother call me." She never did, and I didn't see him again.