Update EEWB (z-fields) on BP Relationship via FM / BAPI's
are there function modules (BAPI's) with which we can update customer fields (generated by the EEWB). Via the GUI it works just fine, but for updating them via BAPI's is giving me some hard time. BAPI_BUPR_RELATIONSHIP_CHANGE is jsut for the standard SAP CRM fields, but so it seems not for customer fields.
There is a BAPI for updating CI-fields on the BP itself (BUT000) but I can't find one, or an alternative for the BP relationships. I have tried it with BUPA_INBOUND_REL_SAVE, which actually holds all the fields including the Z-fields. But I can't seem to get it to work.
Any suggestions, alternatives, etc...