The dates refer to the old calendar used in England and the American colonies before 1751. The year began with March 25, and the Quakers refused to use the name referring to the Roman god, calling calling March, April, May, and so on, month 1, month 2, month 3, etc. To translate to the current system requires adding eleven days, meaning Martha's birth on 6th day, month 6,1696 would be 17 August 16946. The marriage on 17th day, month 9, 1698 would be 28 November 1698.
Birth of Martha, daughter of John Siddale and Abigail, his wife: Martha's birth second in 1696 list
Marriage of Abigail Mattern and John Bettle: about halfway down second paragraph, 1698
John Bettle Will: Abigail Mattern deceased before April 1715; ". . . silver cup and spoon that were her mother's. . . ."