It might be worth it to try to find the birth records of Edith and Cecil to get better confirmation. In 1880 female daughter appears to be the Edith in 1900 living with widowed Thomas and widowed grandfather Russell.
Thomas Fields Military Papers list Cecil as son and his brother Albert as nearest living relative. All the pieces seem to fit , but not actual proof. Did not find marriage record for Ewina and Thomas, or a death record for Ewina. His burial is listed on his military papers, maybe finding that record would tell more? In 1880, 1900 and on 1905 Military admission papers Thomas occupation is listed as 'harness maker' which also seems to fit.
US Census, 1850 Pleasant, Grant, IN
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Russel Fields M 37 Tennessee
Fereby Fields F 25 Tennessee
Thomas L Fields M 8 Indiana
Margas A A Fields F 11 Indiana
Aaron S Fields M 2 Indiana
Asa Fields M 0 Indiana
U S Census, 1870 Liberty Twp. Wabash, IN
Russell Field M 58y TN
Ferryby Field F 47y TN
Thomas Field M 28y IN
Aaron Field M 22y IN
Alfred Field M 20y IN
Henry Field M 10y IN
US Census, 1880 Pleasant, Grant, IN
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self Russel Fields M 67 Tennessee, United States
wife Phereby Fields F 57 Tennessee, United States
son Alfred Fields M 30 Indiana, United States
son Henry Fields M 20 Indiana
U S Census, 1880 Marion, Grant, IN
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self Thomas Fields M 38 IN/TN/TN
wife Ewina Fields F 24 OH
dau Bertie Fields F 6 IN
son Lee Fields M 3 IN
daughter Fields F 0 IN ? Edith below
sister-in-law Ada Creviston F 18 OH
U S Census, 1900 ED 34 Franklin Township (excl. Marion city), Grant, IN
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head Russell Fields M 88 Mar 1812 TN/NC/TN Widowed
son Alfred Fields M 50 Apr 1850 IN Single
son Thomas Fields M 58 Jan 1842 IN Widowed
granddau Edith Fields F 20 May 1880 IN
grandson Cecil Fields M 18 Dec 1882 IN
U S, National Homes for Disabled Volunteer Soldiers, 1866-1938
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Thomas Fields
Military Service: Enlisted Feb 6, 1865 Marion, IN
Priv. Co. D.
Discharge Sept. 4, 1865 Lexington, KY
Admission Aug.24, 1905 Marion, IN
age: 63 birthplace: near Union City, Indiana
estimated birth year: 1842
Burial: Home Cemetery January 28, 1919
Grave # 2737 Sec. 4 Row 10
# 2760
Name & Address of nearest relative: Alfred Fields, Marion, IN – brother
Pension turned over to son Cecil Field, 56 Heiskill St., Wheeling, Va – Sept. 23, 1920
page: 8851