Chris,
I can't help you with your distant ancestors, but I can report on your great-great uncle, Bayard Snowden Cairns, who is my step-grandfather. He was a suitor of my grandmother, Belle Whitfield James, in Memphis at the end of the 19th Century. However, she upped and married a Northerner, John Gilbert Willis, in 1893. The marriage didn't last and they were divorced (due to infidelity!) in 1905, one year after my father, Henry James Willis, was born. Belle moved back to Memphis and then to Redlands CA, where she finished raising her three children.
According to family legend, during this time Bayard stayed in Memphis caring for his mother, Mary Jay. She died in the early 1930's, whereupon Bayard travelled to Redlands and finally claimed Belle as his bride around 1932. They moved back to Memphis and two years later Bayard died of a massive heart attack. Belle then moved back to Redlands to care for her mother. She kept the surname Cairns for the rest of her life.
As you know, Bayard was a renowned architect, with his sketches, etc., residing at the University of the South. More family lore has it that he designed St. Mary's Episcopal Cathedral in Memphis, but I can't find anything about that on the Net. Do you know?
I found a neat picture of Bayard with Belle holding me, a newborn babe in 1934 just a few months before Bayard died, in my scrapbook. I can send it to you if you are looking for such stuff. Best, Nicholas Willis