W. J. Downing has her death year as 1754. Quite a difference!
H563 has her date of death as 26 Jul 1806 in Amherst, VA.

Isabella Oliver Morton’s great-grandmother Mary Tinsley, came from another influential family of Virginia. Mary Tinsley’s parents were Edward Tinsley and Margaret Taylor. The Taylor’s and their descendants were yet another prominent Virginia family. Margaret’s father Col. James Taylor II was great-grandfather to two American presidents, James Madison and Zachary Taylor. Margaret’s sister Frances Taylor married Ambrose Madison, grandfather of President James Madison. Margaret’s brother Zachary Taylor, was grandfather to President Zachary Taylor. President Zachary Taylor’s daughter Sarah Knox Taylor was the first wife of Jefferson Finis Davis, President of the Confederate States of America.