George M. Beckwith was a brother to Dan(iel) Washington Beckwith who founded Danville, Vermilion Co. IL. He was also brother of Dr. Norten Hadley Beckwith, Sebastian Beckwith, and 4 other siblings (I do not have my notes here at work). The dad, if I remember right, was Stephen Beckwith. The mother moved to MI with two of the sons. I believe they settled in the Ionia County MI area.
Sorry about the generalizations, but hopefully these provide leads. There was an article on this family in the National Genealogical Society Quarterly back in about 2001. The about 20 page article deals specifically with George, his parents and siblings.