Upgrades to Systems?

Our process at Empirix is to ship out a system, and then we add/adjust hardware and software to the customer-owned system in the field.  We have been processing these via new sales orders, filling out the installation details on the sales order in EBS.  Of course, when we need to do an upgrade in the field that requires that we swap out existing hardware with the new hardware, it becomes difficult.  Many times we are not receiving the old hardware back, we are just sending the new hardware out to the customer site and one of our implementation engineers performs