It sounds to me like you are describing William G. Smock and possibly some of his sons who were born in Somerset county NJ and moved to Macoupin and Greene counties, Illinois. William as far as I can tell was the second son of Folkert Smock b. 1754. Folkert was the third son of Leonard Smock b.1730 and Ann Folkerson, also one of the younger brothers of my 3rd great grandfather Barent/Barnet Smock who moved from Bridgewater Twp, Somerset county, NJ to Washington Twp, Fayette county,PA in 1789.
The town of Smock, PA was built up around my great grandfather's farm stead in Franklin Twp. Fayette county, PA
We all have found some interesting mysteries to solve about our ancestors, mine is why Leonard b.1730 and his wife left Barnet and Folkert in New Jersey when they moved to Pennsylvania in 1761.