Partners not copied from P.REQ to PO

Hi Folks,

When I create a PO directly the 3 partners LF, RS and BA are copied into the PO.

If I create a P.REQ with the same vendor in the prefered vendor field and convert that P.REQ to a PO then only the LF partner is copied into the PO!

Any of you guys that have had the same experience and maybe can explain why? To me it is not logical 😊

Thanks in advance,

Thomas