EVA Poyatos

Hello, we have a doubt with regards to the use of the valuation method to be used when making an import in Northern Ireland when there is a movement of own goods from GB (Free circulated) to NI, based on a pro-forma invoice. Apparently, as there is no sale previous to the import we could not use the valuation method 1, but reading today's update on CDS requirements for data element 4/16 we were wondering whether in this case we could still use valuation method 1. Please, see the note related to this data element: "Note: if the declared value is based on a proforma invoice and the final invoice value differs from the proforma invoice value, the declarant will need to request a post clearance adjustment." Couldn't we in this case use valuation method 1 (proforma invoice) and then request a post clearance request when the sale takes place and we have final price? Given that valuation method 1 also accepts pro-forma invoices we were wondering if we could proceed as explained instead of requesting the application of valuation method 2 (identical goods). Many thanks in advance!