The first thing you maybe should think about is sending an email to Katie Lynch and asking her if it's okay by her if you expand on a story she created. It might, it might not, but it's usually best to get permission from the aauthor before doing something like this. Especially if you're planning on sending it to the webmaster for eventual posting on the Library.
As the author myself of many fanfic/net published stories, I can tell you that depending on the tone of the request, i usually don't have a problem with people being 'inspired' by my fanfics, however, i do have a problem with someone writing, posting, and not asking me first whether it was okay. I don't like not being asked. Perhaps she might have the same thoughts, and in any case, it would still be nicer to ask.