What is the best way to assign a Serial Number to a rework job created from an RMA?
Current Process:
Create RMA (Serial Number is Created)>Create Sales Order (Reference RMA)>Create job with Demand Link to Order.
I cannot retrieve any available SN’s using SN Assignment and being the SN was created in the RMA I cannot also recreate it.
Why are you creating a Serial Number in the RMA? Does the part already have a SN from before?
When parts are returned to us we receive them under a new part number with an addition of an R at the beginning to signify a return (I’ve always questioned this 
) So physically yes that part has a SN when we shipped it out, but it is tied to the part without the R. Therefore when it is returned the R part is serial number tracked and required when creating the RMA. We just create the SN again except for the return part.
We had to use a different part number for reworked parts as we were using average costing.
When the part was reworked and put back into inventory it was leading to inaccurate costs.
Maybe this was the reason?
Even then we found the whole RMA/ rework process far too cumbersome.
In the end we went for a custom application built on two UD tables and kept the serial number as a status of shipped.
In this process, when you create the Demand Link, if do it as Make to Stock (don’t create a Sales Order) then you can check the Misc Shipment box, then when you disposition the RMA, disposition it to that job. Doing so will tie the RMA to the job, thus carrying through the serial number information entered on the job.
Of course, the caveat to this is that you’re doing a Misc Shipment, which means that closing the job has to be done manually to auto-generate the Misc Shipment record and then there’s nothing to ship and invoice against the Order. We do this, but it works for us because we don’t need to invoice our customer for them, so this process allows us to track RMAs without needing to create a Sales Order for them.
Not sure what your company’s willingness is to use the system as intended, but if used as intended Epicor can handle that for you. I will admit that the process is a little clunky, but it does work.
Since your parts are serial tracked, using the “real” part number with the “real” SN will give complete visibility to all transactions against the SN. When you disposition an RMA to a Job, the returned part gets issued to the job automatically with it’s existing SN. I would need to double check, but I believe that the Job is already marked as rolling the SN up to the 0 level. Then you can create the SO to ship out against. The system will track all of those transactions so you have the full history of the part.