I don't have the answer to your question about the parents of Hannah (Douglass) Allen, but I may have bits and pieces. I believe she and Isaac Allen posted intentions to be married on 19 Sep 1801["Isaac Allen & Hannah Douglass both of Freeport, 9/19/1801" from Freeport VR, see p66 in http://www.mainegenealogy.net/2007/01/freeport-publishments-1789-1801.html]http://www.mainegenealogy.net/2007/01/freeport-publishments-1789-1801.html] and weremarried in Freeport 24 Dec 1801 (Cert. Issued).I also have access to Malcolm Allens "Descendants of Walter Allen of Kittery," which may answer some of your other queries posted on Douglas and Freese Forums. I also have a family record from Judge Townsend's copy of Freeport VRs of Isaac and Hannah that answers some (not all) questions.
What is your line of descent from Isaac and Hannah? I come from a tentative dau Eliza-[beth] Allen who was born abt 1801 and m. Charles Lyman Brown. This is NOT the dau Elizabeth Allen b. Freeport 1807 who married Jonathan Field. There's some unscrambling to be done here and I'd be happy to share what I have at SteveElls[at]GMAIL.COM