I was a paid ancestry.com member until about a year ago and I think I have gleaned everything I could. I know new records go online all the time so hopefully, eventually, something will turn up. I'll try military records... that's one I didn't use, but I've been learning that many slaves fought in the civil war. also, I'll look for birth and death certificates for everyone I have so far to see if another connection turns up. I don't think I put that much time into it before... the census records all the children with nicknames, not legal names, too, which makes it harder :(
I'm not sure if Sol was white according to the law, but he was described as a "white slave" in the account I found, and that makes me think he could have been indentured but does not give any good clues as to how he became a slave. he could have been a freeman who was kidnapped and illegally sold, or he could have sold himself to pay a debt of some kind. some of the reading I've been doing on slave traders in the area is completely horrifying so I believe anything is possible.