Unfortunately, our eCommerce platform doesn't allow us to add directly to your order, but if you place a second order and your first order hasn't shipped, we can combine the two orders and refund you the difference in shipping back to your original payment method. This is a manual process so you'll want to:
1. Be sure your first order hasn't shipped (you would have received a shipping confirmation if it did).
2. E-mail us letting us know you're going to do this, referencing this help topic.
3. Let us know your new and old order numbers in the above step so we don't have a hard time looking them up.