I would encourage her to do her own and then do a little touch up as needed with complements on how well she did. I would try to drop "please do this...and just reinforce the intended hair do/behavior. When ever she has her hair pulled back say wow that looks so pretty. Grandmas can be a big help with this. Also give a choice would you like a pony tail or headband today? She might say neither but let it go unless it's important.