I believe I have found enough documentation to name a third child of Dennis Robinson; a female with a first name of Mary, but no maiden surname can be determined at this stage of the research. The documentation follows John Moores, the son of Hazen Mooers, and is mainly census reports at this time (12/22/2011). In the book THROUGH DAKOTA EYES, Anderson and Woolworth state that John Moores, after 1867, settled in Lincoln County and married a sister of Thomas Robinson's. There are severel more references to John Moores in the book on the 1862 Uprising but none that would yet make reference to Mary Robinson. [See footnote 1]
In the 1850 FEDERAL CENSUS for Minnestory Territory, Wapashaw County there is a John Mooers enumerated. [See footnote 2]
There is no 1855 MINNESOTA STATE CENSUS available. [See footnote 3]
A search of the 1860 FEDERAL CENSUS did not disclose an enumeration of John Moores or Mooers so far. [See footnote 4]
A search of the 1865 MINNESOTA STATE CENSUS did not disclose an enumeration of John Moores or Mooers so far. [See footnote 5]
A search of the 1870 FEDERAL CENSUS did not disclose an enumeration of John Moores or Mooers so far. [See footnote 6]
In the 1875 MINNESOTA CENSUS, Lincoln County, Town of Lake Benton there is a John & Mary Moore. Their color/race is confusing; the enumerator used a code of H or N and Ancestry.com determines the code to be Negro! [See footnote 7]
In the 1880 FEDERAL CENSUS, State of Minnesota, Lincoln County there is a John Moore (color White, b. abt. 1824) & his wife, Mary Moore (color Indian, b. abt. 1839) [See footnote 8]
In the 1885 MINNESOTA CENSUS, Lincoln County, there is a John Moore (b. abt. 1823) & his wife, Mary Moore (b. abt. 1830). Their color/race is confusing; the enumerator used a code of H or N and Ancestry.com determines the code to be Hindu! [See footnote 9]
The 1890 FEDERAL CENSUS was almost entirely destroyed in a 1921 fire so there will be a ten year 'location/migration"gap between the 1885 & 1895 Minnesota censuses. [See footnote 10]
In the 1895 MINNESOTA CENSUS, Lincoln County, there is a John Moor (Indian b. abt. 1828) & his wife, Mary Moor (Indian, b. abt. 1842) [See footnote 11]
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[footnote 1] - THROUGH DAKOTA EYES - Narrative Accounts of the Minnesota Indian War of 1862, Edited by Garry Clayton Anderson / Alan R. Woolworth, Endnote 10, page 216:
John Moores was the son of Hazen Mooers, a trader, and a Dakota woman. He was born in 1826 near Red Wing's village at the mouth of the Cannon River and lived there with his mother until he was about fifteen years old. He then joined his father and learned about the fur trade. They moved to the Redwood Agency in 1853, and by 1855 John was clerking for James W. Lynd. He was active in the war proteching the captives and spent the winter of 1862-1863 in the Dakota camp at Fort Snelling. After scouting for the army, 1863-67, he settled on a claim in Lincoln County and married a sister of Thomas Robinson's. He died on January 1, 1899.
Sources: A. E. Tasker, "Early History of Lincoln County (Lake Benton, Minn, - Lake Benton News Print, 1936, reprinted 1973) at p.294 & "Tyler Journal", January 6, 1899
[footnote 2] - 1850 FEDERAL CENSUS, Minnesota Territory, Wabasha, District 1, Dwelling & Family 12:
Mooers, John, 30, male, Indian farmer, birthplace Bluefountain, Minnesota. No other family members enumerated.
[John's birth date calculated as 1820.]
[footnote 3] - The 1855 MINNESOTA STATE CENSUS for heads of household has been largely lost. The published schedule for Wright County has survived, as have manuscript copies for the counties of Chisago, Doty, and Superior.
[footnote 4] - Although nothing has been found so far in the 1860 FEDERAL CENSUS, the book THROUGH DAKOTA EYES has entries for John Moores living in the Lower Sioux Agency area.
[footnote 5] - 1865 MINNESOTA STATE CENSUS. Minnesota state enumerations now include all members of the household. Also in 1865, “Soldier or Sailor in service on June 1, 1865” was included.
[footnote 6] - 1870 FEDERAL CENSUS. More searching line by line needs to be done on this census for John Moores. But he could have been moving and missed by enumerators.
[footnote 7 ] 1875 MINNESOTA STATE CENSUS, Lincoln County, Town of Lake Benton, Family No. 5:
Fred Brull, age 19, male, color white, nativity Wisconsin, parents nativity New York
C Brull, age 18, female, color white, nativity Pennsylvania, parents nativity Pennsylvania
William Brull, age 11, male, color white, nativity Minnesota, parents nativity New York
John Moore, age 49, male, color H or N, nativity Minnesota, parents nativity [dashed]
Date of birth calculated as 1826
Mary Moore, age 43, female, color H or N, nativity Minnesota, parents nativity [dashed]
Date of birth calculated as 1832
Eleza Moore, age 7, female, color H or N, nativity Minnesota, parents nativity Minnesota
Martha Moore, age 75, female, color H or N, nativity Minnesota, parents nativity [dashed]
Fanny Moore, age 24, female, color H or N, nativity Minnesota, parents nativity Minnesota
[The enumeration form asks for color with no instructions for code. The enumerator describes the five Moore's H or N. Ancestry.com notes that H or N represents Negro.]
[footnote 8] - 1880 FEDERAL CENSUS, Minnesota, Lincoln County, Hope Township, Enumeration District No. 139, Dwelling & Family No. 23:
Moore, John, White, Male, age 56, Head of family, married, Farmer,
Place of birth MN, Father's place of birth MN, Mother's place of birth DC
Date of birth calculated as 1824
Moore, Mary, Indian, Female, age 41, Wife, married, Keeping House,
Place of birth MN, Father's place of birth MN, Mother's place of birth MN
Date of birth calculated as 1839
Robertson, Samual, Indian, Male, age 23, Cousin, single, Farmer,
Place of birth MN, Father's place of birth MN, Mother's place of birth MN
Robinette, Theo., Indian, Male, 20, Cousin, single, Farmer,
Place of birth MN, Father's place of birth MN, Mother's place of birth MN
[footnote 9] - 1885 MINNESOTA CENSUS, Lincoln County, Hope, District 2, Family 19:
John Moore, age 62, Male, Color marked H, Place of birth MN, Parents not of foreign birth
Mary Moore, age 55, Female, Color marked H, Place of birth MN, Parents not of foreign birth
Mattie Moore, age 35, Female, Color marked H, Place of birth MN, Parents not of foreign birth
Samuel Robinson, age 23, Maile, Color marked H, Place of birth MN, Parents not of foreign birth
Oliver Robinson, age 8, Male, Color marked H, Place of birth MN, Parents not of foreign birth
[Note: The enumeration form asks for color to be marked W, B, M, C or I for White, Black, Mulatto, Chinese, or Indian. However, the enumerator marks the five individuals as H. Ancestry.com notes that H represents Hindu.]
[Footnote 10] No 1890 FEDERAL CENSUS available for Lincoln County, Minnesota. The 1890 FEDERAL CENSUS was almost entirely destroyed in a 1921 fire. Wright County is the only county in MN that has some saved data from the fire.
[footnote 11] - 1895 MINNESOTA CENSUS, Lincoln County, Hope Township, District 12, Family 90:
Moor, John, age 67, Male, Indian, Place of birth MN, Occupation Farming, Scout during the Rebellion
[Birth date calculated as 1828]
Moor, Mary, age 53, Female, Indian, Place of birth MN, Occupation Farmers wife
[Birth date calculated as 1842]
Moor, Oliver, 18, Male, Indian, Place of birth MN, Occupation Farming Carpenter
[Birth date calculated as 1877]