Hello-I have researched some of this. I too start at Thomas Daby born in Salem, who died at Stow. Thomas did marry the Mary Brown you reference. I cannot find a connection between Thomas and any other Daby/Darby/Derby. According to the Derby geneology there were several early Derbies in America. One, John Derby came over to America in 1671, so he obviously couldn't have been here to father Thomas. There is a John Derby who was in Marblehead and I have found his probate record. There is lastly a Thomas Derby who founded the First Church of Salem in 1665. He has to be the son of either John or Thomas but I can find no records of his birth. I have a public tree called "Solomon Pierce". I have the will of Mary Browne's father which has a lot of references to his son in law Derby. Nancy Hopkins