Solution : https://service.sap.com/sap/support/notes/858239 (SAP Service marketplace login required)
Key words : 
normal info record, sc purchasing document, subcontracting info record, terms eine-esokz, net price deriving, correct product version, production version overwrite, production version assigned, material average price, info record
Related Notes : 
       
| 458606 | FAQ: Subcontracting in purchasing |