Hi I am wondering if it is possible to update a field in the purchase order after recieving the coresponding supplier invoice.

My problem is that the purchase order is not linked to the supplier invoice, because the invoice is recieved after the supplier has processed the purchase order.

I would like a field in the purchase order with the unit price of the supplier invoice, because that price might be different because of volume discount, or unpredictable amount of man hours used.

I am using openerp 7.0-2

Question: Can I link the supplier invoice (account.invoice) to a purchase order so I can use field in account.invoice.line?