Dear,
Its strange process you want in SAP.How the initial process starts? From where the requirement of procurement starts,I mean who tells your customer what material and how much qty is needed for whom in your organization.
Is there any third party toll you are using to accommodate the P.O details sent by your customer? and GRN for the P.O once you receive the material from your Ware house person?
Is any one cross verifying that same P.O material was delivered and it was verified by Ware house person? How you are dealing with rejection of materials in case vendor sent some material with wrong technical specs?In that case how you are doing billing to your customer and vendor?
Need more deta8ils to guide you.Kindly update me on this to suggest you the possible options.
Regards,
Pardhu