Dear all ,
If we want that a perticular vemdor supplies an item but bill is produced by other party but again payment goes to first party only (second case : payment to second party only). How this is possible and whether we will have to define second party as vendor also.
There is a partner function tab at the header of PO, you can enter Partner function PI - Invoicing party and GS - Goods supplier and enter the partner (vendor code) different if both are different and enter same if both are same.
I hope this solves ur problem.