Solution : https://service.sap.com/sap/support/notes/92105 (SAP Service marketplace login required)
Key words :
additional key words me57, single purchase order item, enter table t100, enter message number 579, enter message number 580, standard ordering functions, advance program correction, call transaction sm31, choose 'individual maint, purchase order items
Related Notes :
| 109143 | MD04: Multiple purchase orders of SD PReqs is possible |