A similar thing happened at my Catholic High School class graduation but the outcome was somewhat different. 10 minutes before the ceremony was to start the Principal(a nun) pulls a girl from the line (pregnant - and showing)and announces to us that she will not be allowed to participate in the ceremony. Evidently, the Bishop was able to make it to the ceremony afterall. Our class President walks up to the Principal and says if she doesn't go we all don't go. Our entire class was only 75 students and we were all very close to each other. There was no doubt that we wouldn't have walked if she was pulled. They Principal was caught between a rock and a hard place. If we didn't walk she'd be embarrassed and if the Bishop noticed the pregnant girl then she's also be embarrassed. So principal just walked away, the music started to play and the cermony went off without a hitch.
JBR
Class of '75
I applaud you and your classmates! Way to go.