Refusal of payment to the family of a missing serviceman

I carefully read about a case where a son was denied payments because he allegedly failed to provide a certificate of cohabitation with his mother, a servicewoman, who went missing. However, the court recognized that confirmation of cohabitation is not included in the list of mandatory documents according to Procedure No. 884, and such a requirement is superfluous. I have a question: if I am in a similar situation with a missing military relative, can I be lawfully denied payments if I am required to provide documents not listed in the established Procedure? What should I do if the military unit still insists on such documents?