I'm a Singapore company and i buy China-made product for resale to other ASEAN countries. I used to get the FORM E from the factory but i do not send the original to my buyer. Instead, i issue an official letter stating that the good being supplied originates from China citing the invoice number and selling price etc. Now my buyers tells me that they need the original FORM E. Giving him this would mean letting him know the true buying price and the details of the factory. My question is:
a) Can the letter i issue be submitted to the relevant countries' custom for preferential tariff concession?
b) If the above is not possible, what alternative do i have?