Well, what do you do in such a situation? Impose on friends, of course.
I took off with soon to be Mr. Fire Alarm and three others while CrazyMom went to the school in search of a friend (a.k.a. victim). She found a family to collect Miss Bookworm after the concert and gave them our video camera to capture the event for us.
Later, on my way home from church, there was a flurry of cell phone calls between me in the car, CrazyMom at urgent care, and our gracious friends leaving the concert with Miss Bookworm. I am not sure how people survived before cell phones.
As Pa Ingles always said, "All's well that ends well." And we have a video of the concert to boot. (My deepest apologies go to the composers for chopping out a few random seconds from their master compositions.)