I still don't have any information on Henry Dow's parents but I want to share the following information with you, to keep you updated:
Ann/Annie Gallagher born Parish of Kent, Andover, New Brunswick 1821.Ann married James McNeal/Neil in 1842.On the 1851 New Brunswick Census Victoria County, Lower Andover & Tomlinson Settlement, Ann and James McNeal/McNeil are listed with a Nancy Dow, age 14.On the 1850 Census of Aroostook County, James Dow age 11 is listed with Anne's half sister, Elizabeth and her husband James Shay.Ann's mother Nancy and her stepfather Michael Somers are also listed with the Shays.
Henry Dow exited Ann's life between 1838 and 1842.
I have verified that Nancy Dow was the daughter of Annie Gallagher and Henry Dow:
In the Caribou Library book of Local Cemeteries is the following:
High Pillar Stone: CIVIL WAR SOLDIER Thomas G. Walton I Son of Issac "David" & Elizabeth [Post] Walton GAR died Dec 23, 1904 His Wife:Nancy Agnes [Dow] Walton Daughter of Henry & Annie [Gallagher] Dow Jan 27, 1879 41y 5m
So, Henry Dow and Annie Gallagher had two children, Nancy Agnes Dow born 20 September 1837 and James Henry Dow born 24 August 1838/9.
I am focusing on Henry now and will let you know what I find.