(a) With the authority granted by 38 U.S.C. 2409,a,who.12(a) and:

(1) Who are missing in action;

(2) Whose remains have not been recovered or identified;

(3) Whose remains were buried at sea, whether by the member's or veteran's own choice or otherwise;

(4) Whose remains were donated to science; or

(5) Whose remains were cremated and the cremated remains were scattered without interment or inurnment of any portion of those remains.

(b) When the remains of a primarily eligible person are unavailable for one of the reasons listed in paragraph (a) of this section, and a derivatively eligible person who predeceased the primarily eligible person is already interred or inurned in Arlington National Cemetery, the primarily eligible person may be memorialized only on the existing headstone or on a replacement headstone, ordered with a new inscription. Consistent with the one-gravesite-per-family policy, a separate marker in a memorial area is not authorized.

(c) When a memorial marker for a primarily eligible person is already in place in a memorial area, and a derivatively eligible person is subsequently interred or inurned in Arlington National Cemetery, an inscription memorializing the primarily eligible person will be placed on the new headstone or niche cover. Consistent with the one-gravesite-per-family policy, the memorial marker will then be removed from the memorial area.