I read Adam Black's will (which can be found at: http://home.netcom.com/~fzsaund/black.html
while it does list Mary Sights, it does not identify Mary as a daughter, it says "I do allow Mary Sights & Catren Mock Eatch of them to have ten pounds." ALL the other persons in the will are specifically identified by wife, son, daughter, etc. It also says give and bequeath when naming those family members. But for Mary or Catren it says allow, not give or bequeath. If they were also his daughters why would he list the others as family members but not these two? While having your name in someone's will can infer family members, it does not positively identify that person as a blood relative unless it says so or you have some other documentation. Everything I have found says that Jacob Sights had one wife, Mary Elizabeth Preston. Jacob and Mary had two daughters namned Mary and Catherine who were both born in North Carolina.