Give her her own account and let her do what the hell she wants.
I was sick and tired of cleaning crap up after my parents had been on my machine so I set up their own account so I didnt have to deal with it everyday.
Now I just occasionally look at the disaster area they have created and clean it up now and again so nothing gets messed up. 🙄
Shame Apple doesnt do a MacBook FamilyPack, you know pay £50 extra for 4 more computers. 😀