I have a question about musicals. I think I read that when a show is in previews it can still make changes, but once it has an opening night, everything has to be locked and stay that way throughout the history of the show. Is this how it is with every show that is on broadway? Is there a reason they can't make changes after that? Are there exceptions. I know people have mentioned that they've added and deleted lines from Annie over the years. Is this common?