Solution : https://service.sap.com/sap/support/notes/1448678 (SAP Service marketplace login required)
Key words : 
revenue-generating billing document, payment request billing document, billing type 'faz', attached consulting note 22808, attached copying requirement, payment request, copying request, copying requirement '20', copying requirement, system ignores
Related Notes : 
       
| 22808 | Transferring formulas |