Your uncle Edmond is listed in the Nat'l Archives Marine and Navy KIA database. Unfortunately, they do not include serial numbers in that info. Also unfortunately, he is not in the ABMC database (which does include serial numbers).
You might try to get his death certificate from the Marine Corps. I believe you do so at this contact (I'm not sure what info you'll have to give them to get the certificate):
Marine Corps Commandant Code M-HP-10 Headquarters Marine Corps 2 Navy Annex Washington DC 20380-1775 Phone 703-696-1177 Fax 703-696-2072
As for your uncle Walter, he is listed neither in the Nat'l Archives Marine and Navy MIA database, nor the KIA database. I did the search for Michigan. Was there a chance he was listed as from another state, or in a different branch of service?