ECC - Purchase Order - several delivery addresses for one storage location

In our company there are often many storage locations belonging to one plant. And some of the storage locations have several delivery addresses (defined in customizing, visible in table TWLAD, stored in table ADRC, ADDR GROUP CA01).

We have a very old modification in place which results in showing a popup window for all delivery addresses to one storage location. The user can select one which is then stored in EKPO (>ADRN2, if nothing is changed manually).

As this modification is very old now and "behaves" sometimes very strangely, we would like to get rid of it... Nevertheless, the process hasn't changed. It is still necessary to select an address out of a several existing addresse belonging to a storage location.

Looking up the addressnumber and typing it in the address number field is no option - too complicated.

Does someone know a solution / another way besides a modification (I found nothing adequate in the notes or KBAs)?

Thank you in advance.