i really like you baba lolJasper, if you have a hard time verbalizing what you said, you could just show her your posting, it's well thought out and respectful.
And the others are right, only she can choose how she'll respond. And her response says more about her than about you. I say this as a mother
It's hard to let your kids do what you think isn't good for them. But that's our job once they are old enough to live with the consequences. That said, she may decide that she cant live with dreads, or live with dreads supportively and you may have to make other choices.