I'm trying to find a way in 3.0 to create an invoice based on actual shipments, but I don't seem to be able to relate an invoice to a shipment.
Situation: A customer made a big order in April. The sales transaction was recorded using Sale. The price and other details were confirmed and recorded in tryton. The sale was confirmed and processed. The draft invoice was created. It was verified and posted, and sent to customer for payment, with a particular term of payment. Customer paid the 1st installment of the invoice. 1st shipment of the 2-shipment purhcase order arrived from supplier's warehouse, and was shipped to customer. After receiving the goods, customer re-negotiated prices and payment terms. 2nd shipment arrived from the supplier, and 1st part of it was sent to the customer, followed by 2nd part few days later. Now there is a need to issue a new invoice based on the actual shipped quantities, and taking into account new re-negitiated conditions, including discounts and payment terms. When I try to create it Financial > Invoice > New Invoice, entering all the details, and try to use the Realate, I get there only "Purchase" or "Sale". There is no "Shipment". What is the correct way to create a multi-shipment invoice? What is the correct way to handle a situation where customer re-negotiates the purchase terms and discounts after the invoice has been issued?
