For your information the 1973 fire at the NARA affected only Army and Army Air Corps and later Air Force Service records.
Navy (sailors) and Marine Service Records were not stored there in 1973 so are not affected not destroyed.
Merchant Marine records to this day are not stored at the NARA and the address you have posted. Here is a website where to get copies of records. http://www.usmm.org/contact.html#contact3http://www.usmm.org/contact.html#contact3
NARA Website about records destroyed in fire: Army: Personnel discharged November 1, 1912, to January 1, 196080% destroyed. Air Force: Personnel discharged, September 25, 1947, to January 1, 1964 (with names alphabetically after Hubbard, James E.) 75% destroyed.
What you have suggested is noble but inaccurate, unwise and actually your goal of "helping" can not be accomplished.
I have dealt with allot of Government bureaucracy in my time, Veterans, Military, and Social Security. It is my understanding the NARA is a storage facility of Records as they are complied by the various Government Depts that send records them to be stored there. They do not compile, generate or change what has been given them. It is not in their mission statement. They CANNOT place, change or include any "outside" records, papers or information, in any file given them by any of the Military Branches of Service. Especially if that information is third hand.
So I would not recommend anyone send anything to the NARA as they won't know or can't do anything with it but send it back to you or shred it. With a ID Theft problem one shouldn't send personal information about oneself or others to any organization unless it has been requested by a specific person for a specific reason.