Invoice(s) used to make an export declaration from UK

Hi, One of our UK suppliers edits one export declaration (EX) per order/invoice. Which means if they ship 3 orders at the same time, they edit 3 EX (export declarations). We asked this supplier to do only one EX per shipment, even if there are 3 orders/invoices in that shipment, but they said they do not have any “customs authorization” to do so. At the same time, we have noticed that with some of our other UK suppliers, there is only one EX for several orders/invoices (which is more useful when clearing the goods here). Do you know if there is a special customs authorisation to do so (to use 2 or 3 invoices in one same EX) or is it automatically authorized to use several orders/invoices in only one EX (= one shipment) ? Thank you,

Hi SamanthaL&L Celse,
We would advise contacting the Customs and International trade helpline on 0300 322 9434 if you have any other issues with your query.
Thank you. 

Hi There is not any customs reason why an export consignment cannot be supported by more than one invoice. Provided all the correct vales and goods quality etc are declared on the export declaration that should be fine. There is no customs approval available or needed for this. The reason may be commercial and to do with how your supplier handles such shipments. You would be best discussing this with them.