"I've just been going through the site and documenting the parents of the people I do find, using other people's trees."
Using other trees does not 'document' anything.
If you want a 'fun' approach to your daughter's ancestry, just look at the other trees. There is no point in creating your own compilation of the same mistakes, inventions and fantasies.
Be completely aware that the tree hints offered by Ancestry.com will nearly never point to factually accurate relationship-schemes, and even more seldom than that give you evidence for something.
If you should ever want evidence-based genealogy, here is one place to start:http://genealogy.about.com/od/basics/a/rules.htm
It can be fun, combined often with hard but very rewarding work.