Is there a law against teens harassing adults on facebook?

I had made a group to help find a missing teen in our family.One of the child's friends were added by the missing child's sister on the site I made.On a comment the mother of the missing child made (which I didn't know it was a teen then) the teen came in saying some horrible things to the mom in that group,I remarked in the group that this is uncalled for and deleted the comment.Then I deleted her, feeling they don't need this.In being upset I deleted her ,the teen came to my messages in facebook getting mouthy with me for doing so,at the same time asking to add her back in to the group.Telling me she will continue the running her words on that parent that nobody will stop her,but she should have done it in a message.I tried to let her see the adults side of the way she is acting each time she wrote me again, then I block her after a few letters I answered back of her being rude. she just wasn't going to be helping us, other then placing the parent in a deeper depression. This teen will be a adult in a year she has a child,and a mother of a correctional officer.Which wrote me telling me see will have me will be in trouble for threatening minor ,all I said was to have cops check her out and too get her on harassment first because she was on a mission. I seen her once before on the group talking but never really checked her out till she made rude remarks hurting the mother of a missing teen.Telling me to stop looking for her near the boyfriend he has no idea.Also saying she will help the teen stay away from her parent if she could.The girl missing was out of control not wanting rules.Yet she is missing in a bad area where allot of girls are disappearing right now.Not one cop knows anything or seems to be looking much,So we can't leave a stone unturned.The teen hasn't been seen by even the boyfriend from what the boy say(not believing anything yet)How can I keep some teens from harassing myself or the parents on facebook.When all we need is the news out there with her face on it.Because when I talk to them in my messages they send me first, I get reamed..This law the teens being bullied by a adult I sure feel they need it,But what about a adult being pushed by a teen where's that law.