Thanks for your prompt reply. Some interesting connections are beginning to emerge from the fog. There is an Andrew Telghman Niblett born South Carolina around 1804 reputedly to a Tillman Niblett whose family have not been discovered. If this is the same Tillman Niblett who is the father to Abel and Edmund then a logical, if not proven, connection starts to show up.
I am beginning to believe that the family origins are from a transportee from the UK rather than descendants of the first family of John Niblett and Mary Washbourne. Joel Niblett looks to be a strong candidate.