Solution : https://service.sap.com/sap/support/notes/393343 (SAP Service marketplace login required)
Key words : 
additional key words tas, attached source code corrections, earlier releases refer, individual ordered material, document item level, purchase order item, item level, purchase order, -party material, document item
Related Notes : 
       
| 734066 | |
| 204190 | Third-party: No update of purchase order with SP change |