I have nothing to add except I am a Blackstock descendant on my dad's side. My GG grandmother was Sara Della Blackstock, born somewhere around 1876-78. She was the daughter of Richard and Mary "Polly" Howell Blackstock. My dad's mother is Della Louise, she's named for her grandmother :)
The children I have found are:
Sara, John, Elizabeth, Nancy, Martha, James, Cannie, Debbie, and Mathilda (in no particular order).