"My understanding of this story is that the mother that raised Hannah told her on her death bed that she was not her natural child." That's my understanding too. I haven't found a lot of information about that I'm afraid. I'm not sure if the nanny's name was actually Dock (or Duck for that matter) or if that was an alias she used after she went to Nova Scotia. It was always been described to me as a kidnapping but if it happened at all, the woman may have actually adopted Hannah rather than kidnapped her; it's hard to tell.
Where did you find the Flemings' graves? I don't have a lot of information about them either; that's kind of where I hit my wall on genealogical data.