It depends on whether or not you have more than one supplier for an item. See Transaction ME59 Help for automatic creation requirements. ME56 or ME57 is used to manually select a list of requistions to assign to a vendor and then convert to POs.
Register Hereor login if you are already a member
would it be possible to have a multiple purchase order using a me59 transaction with reference to a PR?
PR = 100 quantity
PO1 - 25
PO2 - 25
PO3 - 25
PO4 - 25