PO Output Message - Question?

Hi Experts,

We have a business requirement.

Our client is MFG industry. Their suppliers (Vendors) are also equally bigger concerns.

So, sometime PO's are sent to supplier corporate office and sometime PO's are required to sent to supplier manufacturing plants. Both are different locations / addresses.

I understand, we have SAP Partner Function can be used to map these. If we maintain partner function settings every PO will have Main Vendor and Ordering Address and Goods Supplier and Invoicing Party.

But my question is, how we will determine or inform system to generate SAP PO Output Messages to sometime to Main Vendor and sometime to Ordering Address. Also, how we will pick up the same in PO smartform as well?

Thanks

RS