We will have our store set up so that payment is at sale - meaning order is authorized and paid at time of order - so invoices will be automatically created. We do this because all of our products are custom products, and we get payment before we complete the work. We frequently have customers make changes to their orders before we ship - which could involve additional costs (or credits). Is there any way to edit an invoiced order, and have the difference in order amount automatically be charged (or credited) to the customer as the case may be?