I'm assuming that Medicare is prime. Based on that assumption it sounds like Tricare is not aware of Mail Handlers. I would contact Tricare to see if they are. With the companies you are indicating it sounds more like an overpayment than a patient credit. If one of the policies is a privately purchased insurance then the patient would be entitled to the credit. But I would want to be sure before I sent the patient any money. If they come back and ask you for the money and you gave it to the patient that will be a sticky situation.
Michele