IS-U CCS: How to make POD fields mandatory in transaction ES31?

Hi all,

I am having trouble implementing a user-check for POD in our IS-U CCS installation release 46C / 4.64:

We want the fields for the point of delivery in transaction ES31 to be obligatory. I am using enhancement EEDMUI02, but unfortunately user-exit EXIT_SAPLEEDM_UI_EXT_TYP2_001 for customer specific checks is not triggered unless input has been made in the fields for POD. I do not want to modify the screen and make the fields input mandatory, because the field values usually can not be filled in manually but are determined by function EXIT_SAPLEEDM_UI_EXT_TYP2_002 (proposal for POD)

Has anybody done something like this before?

Thank you for your help & kind regards, Kathrin!