I am not sure where they got the information on Samuel Agnew, Born 29 Jan 1738.
Samuel Agnew, Born 1738, married Elizabeth Seawright, daughter of Andrew Seawright, Sr and Mary Eleanor Dickson, and located to Greenwood Co, SC, Abbeville, SC area and raised his family there.
It is well documented that this Samuel Agnew, b. 1738 was the son of Captain James Agnew amd Rebecca Scott. I will get back to this later.
See book Greenwood County Sketches byt Margaret Watson.
Samuel (1738, 1791) is a Patriot of the Revolutionay War! Sources Forty-Sixth Annual Wyatt Reunion Combined with Allied and Associated Families, June 15, 1952, Greenville Presbyterian Church, Donalds, SC (17)