One PO multiple vendors

We have a process, not currently in SAP where we would issue one purchase order for a product but pay two vendors.  It is not currently in an ERP system, so the manual entries are made how they need to be made.  We are trying to get this same process now into SAP.

Example:  quantity of 10    PO value 1000 for the cost of the product

                in the value of that $1000 is $900 for the actual product and $100 for sourcing.

                The full value of the PO ($1000) must go into inventory

                We will issue two checks to two separate vendors for the above amounts ($900 to vendor 1,  $100 to vendor 2)

Has anyone had this situation and how did you handle such a posting?  We need to get a posting to both vendors so we can clear the payment made to each from that vendor account.

Thanks