How about just taking a ready to wear pant that she likes and ripping it apart for a pattern. that or....if you already have some ready to wear just applique stuff on them. There are these jeans that are all the "ooak" craze right now. They are called Mosaic or decoupage pants.
http://www.youcanmakethis.com/info/e...page-Party.htm
http://www.youcanmakethis.com/info/e...osaicJeans.htm
You could also do rouching/ruffly stripes around the bottom of the leggs,
http://www.youcanmakethis.com/info/e...ade-Simple.htm
Make some rumba ruffly pants like this
http://www.youcanmakethis.com/info/e...ed-Gauchos.htm
This is how I make Kenzie's jeans fit her for an extra month or so! lol
http://www.youcanmakethis.com/info/e...-Tab-Jeans.htm
I LOVE these
http://www.youcanmakethis.com/info/e...aggy-Weave.htm
All of these ideas are really easy to do, no need for a pattern and they can all be done with ready to wear pants! I have been decorating pants for my six year old. When she entered Pre-K the teachers couldn't help them with their pants, well I couldn't find "cute" pants in her size with elastic waist. So I had to improvise!
Why is it that we can find "little" girl pants that are cute and have elastic but bigger girl pants are boring with elastic!