since when did jack&sally have children? did fans just make it up or did tim burton himself make it up?

Actually, on the official film soundtrack CD, there is an epilogue stating that "many years later" Santa returned to Halloween Town to visit Jack, where he discovered that Jack had "four or five skeleton children at hand" who play together in a xylophone band. Given the ending of the movie, it can be assumed that these children are Jack and Sally's. I got this from the wikipedia page

As for the actual children such as Judy, I think they are just made up by fans. Hope this helps. :)

FANS!!!!!!!! I HAVE ONE!!!!

he had 4 or 5 kids, it says in the lost ending