I don't believe Amanda is the daughter of Isaac Smith and Lucy Otis, but the daughter of Isaac Smith and Lucy Vorce. Both couples lived in the same area at the same time, but Amanda's name is in the front of the family bible of Isaac Smith and Lucy Vorce. Are you on Family Search? Check out Amanda (K2XP-RSH). It lists the same 5 children that you have, and the Provorse spouses.