Solution : https://service.sap.com/sap/support/notes/367080 (SAP Service marketplace login required)
Key words : 
temporary quantity assignments loads, additional key words transactions, attached source code corrections, reference type /sapapo/trguid, radio button 'data type', component type /sapapo/pegid, connected oltp system, prerequisites solution prior, function module interface, call transaction se11
Related Notes : 
       
| 376127 | Temp.qty assgts retained after BOP result transfer | 
| 375193 | Backorder processing: Composite SAP note on posting | 
| 367335 | Delta records during transfer of the BOP results | 
| 365458 | No update of changed orders in APO | 
| 365424 | Incorrect updating of APO backorder processing in R/3 | 
| 147252 | Transferring transactionsid APO->CORE->APO |