In going through my notes and the genealogy book, yes, it pretty clearly states that Christena Mertz was Adam's step daughter, as well as his sister-in-law. She was born about 1850, and married to Adam's brother Johannes (aka John) Axline/Exline abt 1771 (as I think their first child was born in 1772). Her year of birth is taken from her headstone in New Jerusalem Cemetary in Lovettsville, VA- which gives her age and death date- 78 years old on the day of her death April 16, 1828. This is further supported by excerpts from her diary which tell of an account in which the British confiscated some of their things after John made gunpowder.Incidentally, you might be interested to know that John Exline's will mentions his deceased daughter, Elizabeth May's children: Joseph Smith, John May, David May, William May and Leander May. Will look some more and try to post some more information for you.