I looked up your W James Blackwell in some books I have and came up with the following (if you don't already have it):
There is a death certificate for William James Blackwell in Alligator Township.Born 27 Nov 1858 and died 16 Oct 1924. Son of George W and Sarah Ann Blackwell.
Appears that he is buried at the Union Methodist Church (near McBee) along with both his wives: Martha Ann (b. 21 Jul 1858, d. 4 Feb 1896) and Mary Margaret (b. 1876, d 1953).Both have inscriptions on tombstones "Wife of WJ Blackwell".