Saw posts about Samuel while looking for Isaac. I believe that Isaac (jr), Jonathan, Samuel, Thomas and William are all brothers and sons of the Isaac Weldon shown on the 1920 census as transcribed on USGenWeb. On this census of Boone Co there are only two Weldon families, Isaac (who is age group pre-1774) and William, his son.
I am directly descended from William who moves to Clark Co., IL in 1840's.
Dan Engle, Jefferson City, MO