Editing Order after submitted to payment gateway

Is it possible to edit orders after the order has been submitted to the payment gateway?

Scenario.

Sometimes we have customers that place an order but call us later to add other products to the order.

Or a customer does not add the coupon code, but call us requesting we apply the discount.

Is there a way to edit the same order the customer placed?

Does anyone know how to achieve this?

We are currently using Quickbooks merchant account, but would consider authorize.net if it gives us that possibility.

While you can edit orders in Zencart (using a mod), as far as I know there's no way to change a CC transaction after it has been finalized, for obvious reasons. Any additional charges would require a new transaction.

Even refunds don't affect the original charge - they're a separate transaction.