Lynn - in the past one of the things that has been on the 'forms' is whether an author would be willing to pick up someone else's fic if they couldn't complete it for some reason. I'm not sure how often that has actually happened, but if you started a story and felt that you really couldn't finish it, or had to pull out without even getting started on your story, you could inform the organisers and they would try and find another author (probably one who has already posted their fic)to complete it.
