Good day!
As we are sent out in past, If payment term is L/C and customer need to declare sample in shipping documents, we need to declare the sample into application L/C.
Also if the sample declare on invoice, packing list, on B/L must show as well because avoid the discrepancy with bank. All shipping documents must match.
Another way to avoid the troubles and complicated, We will put the sample innermost of container and not declare in any shipping documents.
But if you need invoice, we can issue invoice as picture below and sent you by e-mail.