What if it was my daughter in a homosexual relationship? If she were the minor and I found out she was dating another, older girl, what would I do?
I hope first that I would be big enough to invite the two for a private and polite chat about where our family morals are and what the secular consequences will be if this relationship continues before the age of majority. I would explain that I am morally opposed to all extra marital sex as well as homosexual relationships. I would tell them that their sexual relationship is illegal if they are more than 3 years apart and that if this continues, my daughter will be removed from the school (that is if she is no longer homeschooling) and I will notify the other girl's parents that I oppose the two being together. I would also individually let my daughter know that if she sneaks out or runs away to be with her "girlfriend", I will have to involve the police and file statutory rape charges against the other girl. I would let my daughter know very clearly that as long as she is under age, she puts her "girlfriend" at risk for arrest and a lifetime of problems including reduced chances at college and career. No child of mine plays the "But I love..." card with me.
Now if it was my daughter as the older girl, I wouldn't even bother with meeting the younger girl. I would simply tell my daughter very clearly what the other family can legally do to ruin her life if this relationship goes on. I may even contact the other family and and find out what they know and what action they may take. No matter what the other family does or says, I will tell my daughter to leave the other girl (at least until the younger one has graduated high school and reached eighteen years of age) or I'll not let her drive the family car, not fund college, and if she is especially belligerent, not post bail should the other family press charges.
As a parent, it is my responsibility to teach my children about the law and the consequences of breaking the law.