I have been researching the Danberry surname and would be interested in any additional information you may have on this family. I did a quick search for John Dow and found the following information.
IGI Record lists John Dow born 31 August 1855, Hillsborough Twp., Somerset County, New Jersey; parents Henry Dow and Terrissa.
The Stephens Family Tree by williebuck23 on Ancesstry.com has Henry Dow born January 1835, New Jersey married to Terissa P. born circa 1834, New Jersey. Children listed for them are John D. Dow born 1855, William V. Dow born 1858, died 20 March 1863, and Oscar P. Dow born September 1860, New Jersey. Parents given for Henry Dow are Folkert P. Dow (1808-1890) and Harriet Moffett (1809-1882).
1850 census for Raritan, Hunterdon County, NJ, page 73A
Terisa Danbury age 17 born New Jersey, living in the household of Hiram Sutphin.
1860 census for East Amwell, Hunterdon County, NJ, page 309
Henry Dow age 26, Theressa Dow age 26, John D. Dow age 5, William V. Dow age 2, and Alonza Dow age 25. The film image is very poor and Ancestry transcribed the surname as Low.
1870 census for Piscataway, Middlesex County, NJ page 376A
Henry Dow age 36, Tressa Dow age 36, John D. Dow age 15, Oscar P. Dow age 10.
1880 census for Bedminster, Somerset County, NJ, page 266.1
Henry Dow age 47, Elizabeth Dow 36, Oscar P. Dow age 19.
1880 census for East Brunswick, Middlesex County, NJ, page 384.4
Charles Smith age 50, Emeline Smith age 48, Charles P. Smith age 23, Lydia A. Smith age 21, Mary E. Smith age 21, George F. Smith age 14, Lavina Smith abe 12, Eva Smith age 9, William E. Smith age 6, and John Dow age 24.
1900 census for East Brunswick, Middlesex County, NJ, page 11B
Charles Smith age 70 born July 1829 head, Emeline Smith age 67 born July 1832 wife, John Dow age 42 born September 1857 son-in-law, Lidia Dow age 40 born April 1860 daughter, Charles Dow age 15 born December 1884 grandson, Emeline Dow age 8 born October 1891 granddaughter, Sady Dow age 7 November 1892 granddaughter. Marriage date for John and Lidia is given as 1884.
The Somerset County Historical Quarterly, Volume III, page 312 has the marriage of Henry Dow and Terressa Danbury as 30 August 1884, by Carrell.