I have a GEDCOM file that can be downloaded on the Postlethwait family with 808 names covering 14 generations. Your Samuel that married Ann Dunbar is in there, but I have no children for them. I would be interested in what info you have so that I might add it to my database for others to use. Find the Gedcom file @http://www.gbso.net/actor/dlfiles.htm from that page you can get to my other online genealogy pages. Look forward to hearing from all concerned.