Here is a link to one family page. I am descended from James Augustus Kennedy. I think some of these dates may be incorrect, but most of the names have checked out .
http://www.brasfield.net/getperson.php?personID=I3347&tr...

Also, check out "Legend of Becky (Kennedy) Cotton" Edgefield Co., SC. Becky was married to a Major Ellis. Her brother Stephen b.1780, was married to Maj. Ellis's daughter. Stephen murdered Becky and escaped prosecution , settling in the Natchez area with family.

Stephen G.(from old Stephen's second marriage) moved to St. Louis between 1870 (census Adams county) and 1882(I have a diary reference to a visit that his niece, my g-g-grandmother made to his home in St. Louis in 1882)
Can this be the Stephen you are looking for?