Hi Jacob,
I'm afraid that this is not possible in another way then mentioned in the note.
Plants are different in CRM then in ECC. When you download plants via object DNL_PLANT, for each plant a BP is created. You will have to work with relationships etc like described in the note.
Is it an option to deflag it as mandatory in ECC?
What you also can do is create a custom field for the delivery plant. Let this custom field populate the KNVV-VWERK field via middleware enhancements. Search for event DE_BALE or check the middleware extension guide where it is mentioned in detail how to deal for this.
Regards
T