Ah, too bad you couldn't get to Jerry, to tell him to not release the seat assignments.
You might mention this to him anyway; it would be a good policy for him not to assume that "a friend of a friend" is entitled to such information, any more than they are entitled to your phone number, etc., from him.
It would be a good educational experience for him, and I am sure you could explain it in a way that doesn't make him feel bad.
But you VERY definitely need to make sure that *everyone* in your group is ready to shunt her aside, because she is going to descend on you. And as pushy as she sounds, she's going to wait for you as you leave your seats, and try to tag along wherever you go.
Get a plan in place!