Hi Chris and Jeremy! The best way to do this is to visit www.compassion.com/firstpayment. In the checkout, you will be asked "Is this your first time giving to Compassion?" Click the bubble that says "No, I have donated to Compassion in the past." This allows you to log in or create an online account so that this new sponsorship will be linked with your already existing account. You're also always welcome to give us a call at 800-336-7676 and we'd be happy to take care of this for you.