Hmm... So it's certain they were married in Lowndes Co. I'm still hung up on her being so far from home. Are you sure she was born in White Co TN? I also wonder about the Indian story. I think we should consider the possibility that she just took the Rigsby name.
I had mentioned that there was an Absolem Rigsby or Rigby in Lowndes Co, but as I look more closely I see he's too young to be Margaret's father. Instead, he might be her brother. His father had three daughters under 10 on the 1820 census, and they were probably under 5. The problem is that Absolem's father was in SC and stayed there. Margaret would have had to move to MS with her brother, which doesn't sound too likely.
Interesting that your Margaret moved to Hot Spring Co. Canada's brother John also moved there. John is old enough to be Margaret's father, but he wasn't married until 1822, and as far as I know that was his first marriage.
I have more info on Canada and his descendants on my web site [link in previous message]. He was a son of Thomas c1760 of Mecklenburg Co NC. Thomas' is one of the bigger branches of the Rigsbys. I know I have more information about Canada in my unorganized notes, too. Right now I'm in the process of going through them all, which should take quite a while.