Why is it suddenly so important to change people's musical opinion/taste?
People like what they like, and you like what you like. If they're not satisfied with their limited music collection, than they'll move on out of their own accord. Not everyone has the need to listen to a lot of music, music you deem 'good'.
First of all, she's a twelve year old, let her listen to the music her friends listen to. I don't think this is the 'wrong' direction.
Most of my friends don't listen to the music I listen to (even though most of it is what I think can be considered 'good' music) but I don't have this need to make them listen to the Pixies, or DFA 1979, or radiohead, or the flaming lips. I'll put it on when I choose what music I want to hear, and they'll put on their music when they want to hear it. We don't go around saying "hey, your musical taste sucks, you should listen to this". We live a fairly peaceful life.