How can I select multiple Mfg Part number against single our part number at the time of PR/PO creati

We are structuring new parts and assemblies to support the transition of cable manufacturing to ABCD –INV Org. There may be a system limitation impacting our ability to structure multiple manufacturers' parts where applicable under one our Part-Number.  If this is indeed the case, can you please explain this perceived limitation and what will we need to do to circumvent this issue (if required) so that the Procurement Organization would not be limited to a single manufacturer/manufacturer part-number when there may be several that are approved for a our Part-Number (assuming of course that the source of these parts are