Use APN number in /SCWM/RFUI Transaction

• SAP used to call it "alternative product number", but recent documents call it "Alternate Part number", in fact both are the same, configuration is the same as well as the functionality.
• Master Data (SCM-APO-MD)
  Number under which a product is managed in the system and which exists in addition to the product number defined when the product is created. An alternative product number (APN) may be a manufacturer part number or an old material number, for instance.
• The Alternate Part number in SAP is important for several features in SAP.
• This is what is used to provide a part or material with another part number, in order to allow for correlation between the part numbering scheme in APO and the part numbering scheme in another system.
• You can actually apply multiple different part numbers. They are added to the Product Master (Global data - /N/SAPAPO/MAT1) on the Properties 2 Tab.

They are created in IMG:

At the moment, Alternate Part Number is only searchable at Product Master transaction, like SCWM/MAT or SAPAPO/MAT1

As EWM /SCWM/RFUI transaction is ABAP dynpro & framework based, you'll need to understand the RF framework from EWM.

The cookbooks here Best Practices and Implementation Tips for SAP Extended Warehouse Management (RF Cookbook in your case) shows how to adapt the ABAP dynpros from RFUI.

I would do this ...

1) identify the required SAP dynpro numbers
2) copy them to customer namespace
3) add the copies to customizing that they are used, test application with this (should work like SAP)

4) add APN field, hide MATNR field and provide code to fill MATNR after filling APN in PAI and code to fill APN from MATNR in PBO
this allows you to use SAP RFUI code w/o change to work with APN because internally MATNR is still used

5) if 4) does not work for some dynpros, provide own RFUI PBO/PAI code to work with APN input
6) if ABAP dynpros up and running, generate ITS mobile templates out of if

Best regards,