If their actions rise to the level of a crime, for example this depends upon their comments particularly about your 16-year-old daughter, you can contact your local police and file a criminal complaint
against them. If their actions do not rise to the level of a crime, you may have a defamation case against them depending upon the statements that they have made online against your family. You can talk with a SC defamation lawyer and ask him or her about the strength of your case. Please get copies of all of the statements that this person has made and bring them to your attorney consultation.
Lastly, you can complain to the moderators of the sites that they are using such as my-space because they may have filters for defamatory comments. Good luck.
I hope that I have helped you and that I have answered all of your questions. Please
ask more questions if I have not answered all of your questions.
Please be aware that my answer is not legal advice, it is merely information.
You and I have not entered into an attorney/client relationship, and I am not
responsible for your legal rights. The only way for us to be in an
attorney/client relationship is if you have signed a written retainer agreement
with my law firm.