Handling discrepancies in purchase date, currency, and amount between a Purchase Confirmation and a zero-rated tax invoice

Our company imports goods from overseas and supplies them to domestic manufacturers without any processing (the manufacturer intends to export them after processing). We have received a Purchase Confirmation from the manufacturer, but the purchase date on the Purchase Confirmation is set as the arrival date at the port, and the currency and amount are listed as the foreign currency and the KRW converted amount from the import declaration. We intend to issue a zero-rated tax invoice to the manufacturer, and we plan to issue it by applying the foreign exchange brokerage announcement rate on the delivery date to the actual transaction currency amount. In this case, the purchase date, currency, and amount on the Purchase Confirmation differ from the supply date, currency, and amount on the zero-rated tax invoice. Please confirm if this will cause any issues and whether we can amend the Purchase Confirmation based on the zero-rated tax invoice we intend to issue.