venu,
Do you want to know - for a proforma invoice, what is the "related" commercial invoice?
From proforma invoice there is no direct link to the commercial invoice.
But from sales order or delivery, there is a link to the commercial invoice.
It is a two step process, and the table to use is VBFA:
First go from Proforma invoice to the Preceding documents (order or delivery)
Second go from Preceding document (order or delivery) to Commercial invoice
