I'm taking a shot here. I am related to many Jacksons in Bishopville, SC on my Mother's side. My Great-Great Aunt Winnie McCaskill married a John Jackson in Bishopville. SC in the late 1800s. They had two sons: John Jr. and David, and a daughter Lita. I'm not sure if they had any more children.
I'm not certain if there is a connection between your Jackson and mine. But there is a strong likelihood we could be related. The Jacksons are a big family in Bethune, Bishopville, Lucknow, and Darlington Sc. It's a possibility Salis and John were brothers. It would be nice to know we are related. If so, hello Cousin :-)!