How sure is everyone that his parents were Isaac Pounds and Elizabeth Pisor? I have carried for years that his parents were John Pounds and Mary Randolph. I notice that someone has Isaac Pounds and Mary Randolph as his parents. I can not at this point find my source, but I am pretty sure I had good reason to have his parents as I did. Is it possible that Isaac after becoming a widower married his brother's widow? That happened quite often in the days.
I, too, have not found any source material, but believe that Isaac was identified in a pedigree sent to me for our grandfather (Ray Clarence Pounds) by Pound/Pounds researcher Leland Pound. As I recall, he had no mother identified for Samuel. I do not know where I found the Elizabeth Pisor connection.