Solution : https://service.sap.com/sap/support/notes/158607 (SAP Service marketplace login required)
Key words :
program change enhance structure bapiekpoa, regenerate function modules ale_po_create, general/r3server/abap/note, p4dgeneral/r3server/abap/note, transfer additional item data, attached program change, enhanced structures bapiekpoa, additional item data, generate purchase orders, set parameter item_add_data_relevant
Related Notes :
402242 | BAPI_PO_CREATE: additional data not cleared |
340028 | BBP: No additionl data transferrd to purchase order |
197958 | BAPIs for purchase orders: Missing functions |