From The Colonial Riley Families of Tidewater Frontier, Vol I: A History of Several Riley Families of Maryland and Virginia by Robert Shean Riley, 1999, p. 348.
Mary Riley, born ca. 1781, died by Dec 1818 married Samuel Abney probably in Edgefield County.They had a son William Henry Abney.
Book says they may have married circa 1802 or between October 1806 and October 1809.A descendant of Samuel Abney by his second wife says that they married between October 1806 and 1809 and that their son dates are abt. 1816 - 1892.He only shows one child for William Henry Abney and his wife Sarah Ann Saunders, a daughter, Nancy P. Abney, born in 1850.
Samuel Abney's brother George who married Sarah Griffin had a son named Isaac (1771-aft 1850).