Enable DFF for subinventory transfer line

Summary:

Customer has requirement to capture external NCR number on sub-inventory transfer lines. I see flexfield is available on sub-inventory transfer line, but I can't see which DFF this is linked to.

Content (required):

Can anybody help with which DFF is linked to the sub-inventory transfer line?

Version (include the version you are using, if applicable):

23B

Code Snippet (add any code snippets that support your topic, if applicable):