Solution : https://service.sap.com/sap/support/notes/758884 (SAP Service marketplace login required)
Key words :
assign purchase order items, transfer technical fields, attached advance corrections, funds reservations, kblnr + kblpos, terms bapi_po_create1, po_price reason, program error, no_rounding, bapi_merge_data
Related Notes :
| 1225535 | BAPI_PO_CHANGE Pricing with B changes price after GR IR |
| 954531 | BAPI_PO_CHANGE: Field values are not transferred |