A buyer changed my document format mid season once. We typed it by hand to the last vessel rather than rebuild anything: you do not touch an invoice while fruit is sailing.
The cost is not software. My invoice has to agree with the plant health certificate, the bank and the customs entry, so any new field has to come out the same way every time.
Ask your buyer for a file their system already accepted and copy that, not the spec. Do it in a quiet week.
