Third party drop ship - change material once Preq/PO is issued

Hi Experts,

We are using third party drop ship process to place spare part orders with our vendors. At times, the vendor could send an exception message (EDI) to correct the material being used as we could've initially sent incorrect material number. So ideally we would want to update the existing sales order line item with the new/changed material that the vendor has sent. This is not allowed as there is a subsequent Purchase requisition and PO linked to the Sales order.

Is there a standard way of handling this? I know we could instead delete the PO and Preq line and reject the sales order, then add a new sales order line with the new material and let the new Preq and PO be created. Since all this is handled automatically via EDI, we would want this automated and hence I was looking for standard options. Also, we would like to use the same PO number that is sent to vendor instead of generating a new one.

Any help would be appreciated!

Thanks,
Nanda