Martha Olivant was actually the third wife of James S. Whigham. His first wife was Saphronia McNair, by whom they had 5 children (the 4 you mentioned plus Kate b:1868). James and 2nd wife Nancy E. McNair had 4 children (your 2 plus Elna Ruth b:1882 and Ruby b:1885. James also had a 4th wife, Mattie Williams. There is also another daughter, Abba, probably with 3rd wife Martha.