The New Hampshire Genealogical Record has an article by George Freeman Sanborn Jr. that gives detailed information on the second wife of Joseph Dow. It totally discounts the work of Robert Piercy Dow in his Book of Dow on this subject. It says that Hannah was actually Hannah Challis, a sister of his first wife. It gives 8 children to this couple. I do not have the date of the publication, but based on a statement at the end of the article which references the date 1988, it must have been published after that time.That statement says that reader should avoid the book Hampton Vital Records and Genealogy, 1889-1986 published as vol 4 of History of Hampton NH (1988) because the section on Dow, pages 35-41, is badly flawed and confused.