My husband's oldest daughter will be turning 18 soon and also has a 15 year old. Should there be a reduction in child support since the payment is based on 2 children? If there is a reduction, what percentage. Should it be cut in half? Does it matter whether the 18 year old goes to college whether there should be a reduction? Is he obligated to contribute to her education if there is no mention of it in the divorce decree? We live in Tennessee, if that matters.