This is information from a Great Granddaughter of William Marks Caller, Judith Caller Johnson. William Marks Caller was, indeed, the son of James Strother Caller. However, she states that he was married to a MARY LOUISE MARSHALL, on December 13, 1878. Mary Louise and William Marks Caller had children. (1) Green Duke Caller (2) Edward Marshall Caller, (Judith Caller Johnson's Grandfather)(3) William Marks, Jr. (4) Mary William Caller (5) Fredonia
James Strother Caller was the son of Colonel James Caller and Winifred Duke Caller. Col. James Caller was my GGreat Grandfather, from his daughter Martha Caller.
Hope this helps with your research of William Marks Caller.