Hi,
Thank you for your answer.
I checked FM CRM_UPLOAD_TRIGGER which is called in ERP when BDoc arrives from crm. Here the Z-field is available. Later on when FM PI_BP_PROXY_BAPI_CUSTOMER is called, it is lost. The problem is in FM PI_BP_BAPIMTCS_TO_REL. Here the Z-field is available in bapimtcs structure, but there is no processing of the custom fields here (of course - it is a standard FM which processes the standard part of BUPA_REL BDoc). However I did not find any user exit at this point.
I have to update field KNREF from table KNVP of the particular relationship.
Any advice how to do that?
Regards,
Desislava