I also was taught to reach behind and wipe front to back. As long as she is taught to wipe from front to back I don't imagine it matters much how she manages to do it. I'm trying to teach my son to wipe at the moment but he just stands up turns around and says you do it. Cheeky sod!
I was taught to wipe myself after going to the toilet by reaching my hand back around, bending to the side and wiping from front to back (I find this a lot easier, but perhaps I just have freakishly long arms). Everyone else seems to wipe with their hands between their legs. My daughter watches me wipe myself after going to the loo, but should I teach her to wipe herself the other way? Is there any scientific benefit to either way?