Try checking the 1871 census of Portland Parish. The microfilm is available by interlibrary loan from the national archives in Ottawa if your library doesn't already have a set. Looking around, I get the following.
MARTHA ELLEN (NELLIE) WHELPLEY b. 23MAR1853 (ca. 1853-4), d. Saint John NB 24JAN1913 age 59 years, m. 1st Portland, Saint John Co., NB by the Rev. Henry Pope 6JAN1874 WELLINGTON MOWRY (b. Long Reach, Kings Co., NB); m. 2nd Portland by the Rev. S. T. Teed 5NOV1878 Capt. WILLIAM ALFRED DEMINGS (b. Bay Verte, NB OCT1855 (ca. 1856), d. Saint John 1AUG1932)
When first married Martha E. Whelpley was from Portland. In the 1871 directory, four Whelpley's were listed in Portland:
Daniel Whelpley, ship builder
Francis Whelpley, Grocer
George Whelpley, master mariner
Titus Whelpley, ship carpenter
Also when first married their marriage bond was co-signed by Stephen H. Purdy. I suspect this was actually Stephen Lane Purdy (b. 10OCT1838 (ca. 1841), d. 21APR1921.) His wife was Mabel Anna Robson (b. 25APR1848, d. 1FEB1937.)
A son may have been Roy B. Demings b. ca. 1888, d. Portland 14AUG1888.
William and Nellie 'Demmigs' were in Portland in 1881. They were in Lansdowne Ward, Saint John in 1891. Next door lived Capt. George Whelpley (b. NB ca. 1835) and his wife, Alice (b. NS ca. 1837.) In 1881 Capt. George Whelpley (b. NB ca. 1836) and his wife, Hannah Alice (b. NS ca. 1837) and family lived in Portland. This may be George Leonard Whelpley b. Kingston Parish, Kings Co., NB 13JUL1834, s/o Titus Brown and Susanna (Oram) Whelpley. While obviously related, George does not seem to be a brother. Possibly an uncle, for example, George Leonard Whelpley had several elder brothers:
David Jonathan Whelpley b. 1823, married 3 Sep 1844 Maranda Purdy:
James Oram Whelpley born 1825:
William Henry Whelpley b. 1827: settled on Long Reach in Kings County:
Daniel Whelpley b. 27 Sep 1828, m. Jerusha M. Cronk:
John Whelpley b. 1832:
any of whom may have been Nellie's father. George Whelpley m. 1868 Alice Sweeney. George L. Whelpley, however, m. 1871 Cassie Clinton Kingston.
They were in Dufferin Ward, Saint John in 1901 as Wm and Nellie 'Deming'. George Whelpley (2APR1835) and Alice (27FEB1837) were in Lansdowne Ward. With them was John Sweeney (19NOV1865) possibly Alice's brother or nephew. If George's date-of-birth is correct, he was not George Leonard Whelpley, but it seems he was the same who m. Alice Sweeney. Presumably he was also the George Whelply, master mariner, in Portland in 1871. He would also be the sea captain in Portland in 1881 (age 45) with a wife, (Hannah?) Alice (b NS ca. 1837), what may be Alice's children by a previous marriage: George Franklin Sweeney (20), Gilford Dudley Sweeney (19) and John Edward Sweeney (16); as well as their children: Minnie Cassie Whelpley (15), Alice Mary Whelpley (10) and Frank Ernest Whelpley (6.) John J. Sweeney m. Tusket River NOV1855 Alice VanNorden, d/o Peter VanNorden. John was from Saint John. Tusket is in Yarmouth Co., NS.
Supposedly Capt. George Whelpley operated a skate factory on the Long Reach, making early speed skates called 'Reachers'. This was actually James Albert/Alfred Whelpley, a different member of the family b. 5MAR1839, s/o Thomas and Maria (Belyea) Whelpley. James did work with his brothers. The family appears to be that of Thomas and Fanny M. Whelply in Westfield Parish, Kings Co., NB in 1851 with a son, Albert, b. ca. 1838. They did have a son, George (ca. 1830) but this is unlikely to be Capt. George Whelpley. Rather he was George Thomas Whelpley, s/o Thomas Richard and Frances Maria Whelpley, b. 1831, bpt. MAR1837. There is no indication that Thomas and Fanny Maria had a daughter Nellie or Martha. Thomas Richard Whelpley was the brother of the Titus Brown Whelpley who m. Susannah Oram above.
1. ARMOUR E. MOWRY b. ca. 1874-5
2. JAMES MAITLAND MOWRY b. 12JUL1876 (ca. 1876-7), d. 19APR1957, m. JEANETTE ALBERTA PARKER
3. MINNIE LOUISE DEMINGS b. ca. 10NOV1879, d. 26JAN1880
4. ETHEL MAUDE DEMINGS b. Saint John 26FEB1882 (ca. 1882), d. Saint John 8NOV1958
5. WILLIAM EARNEST DEMINGS b. Saint John 23OCT1883 (ca. 1884)
6. ROY BERTON DEMINGS b. ca. 5DEC1887, d. 13AUG1888
7. NELLIE A. DEMINGS b. Saint John ca. 1893, m. Saint John 2JUN1913 FRASER A. JOHNSON (b. Saint John ca. 1891), s/o Andrew M. and Annie G. Johnson
8. HAROLD DEMINGS b. 20AUG1897