Abraham Williamson is my GUncle, brother of Henry Williamson, my GGrandfather. I do not have much info re Abraham except that he was the executor of William's will/estate in the 1850's when William died and was born along with brother Cornelius and Elizabeth in NJ. I have a feeling that he appeared in Vermilion County, IL later on, per the census, and must have followed his brother and cousins to IL. Henry came to IL right after the 1850 census as he was in Warren County then, but was not home when his father died.
If you wish to contact me directly, my address is email@example.com. I can send estate info. and family sheets which may help.