Open PO with respect to Partner

Hello,

I have a new requirement given below.

" we have partner data in PO header. Now I want to see all open PO with repect to Parnter fuction."

I tried in EKKO to get relation between partners and PO, but it is not there.

Please tell me correct table to get this relation. After getting this relation, I need to find out open purchase order with respect to this partners.

Thanks,

Kunal