Top, greetings from a retired "Squid." My late colleague, Ed Gerdes, transcribed Martin V. B. Sutton's compiled service record, and noted the reference to the "death claim," as it is informally known. Records that I've personally transcribed include an abstract card giving the bare details of the claim, and is often accompanied by a notorized statement from the claimant -- setting forth the soldier's name, rank and regiment, the date of death, the relationship of the claimant to the deceased soldier, etc. -- and an affidavit from the First Auditor's Office of the War Department which verifies payment of the claim.
A friend of mine who served in the Marines once explained to me the command structure in the Corps. He said, there's God, the First Sergeant, and then everybody else.