In 1918 he is single, living with mother Elizabeth Jane Thompson. From that and her death cert. found him in 1900 living with step father and his mother and 1920 with above parents and wife Mary. Didn't find her marriage to C C Thompson.
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World War I Draft Registration
Citing this Record: "United States World War I Draft Registration Cards, 1917-1918", index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/29JQ-TDN), Alfred Edward Watkins, 1917-1918.
Name: Alfred Edward Watkins
Residence: Analaska, Lewis, WA
Draft Registration Sept. 12, 1918 Chebalis, Lewis County, Washington
White Male Single Age 37
Birth Date: 22 Apr 1881
Nearest Relative: Mother Elizabeth Jane Thompson
Washington, Death Certificates
Citing this Record: "Washington, Death Certificates, 1907-1960," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/N3RD-6L5), Elizabeth Jane Thompson, 20 Nov 1941; citing Mineral, Lewis, Washington, reference 379, Bureau of Vital Statistics, Olympia; FHL microfilm 2023825.
Name: Elizabeth Jane Thompson
Death: 20 Nov 1941 Mineral, Lewis, Washington
Female married
Age: 77 years 10 months 22 days
Birth (Est): 1864
Spouse: C. C.
Father: Julius Nelson King
Reference ID: 379
U S Census, 1900 Dryad, Eagleton, Independence, Lincoln Creek, and Oryad Precincts, Lewis, WA
Citing this Record: "United States Census, 1900," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/MMP2-71Q), Eddie Watkin in household of C C Thompson, Dryad, Eagleton, Independence, Lincoln Creek, and Oryad Precincts, Lewis, Washington, United States; citing sheet 12A, family 189, NARA microfilm publication T623, FHL microfilm 1241747
C C Thompson Head M 38 Iowa
Lizzie Thompson Wife F 36 Mar 1864 Oregon/IN/IN
Eddie Watkin Stepson M 19 Apr 1881 Oregon/MO/OR
Ray Thompson Son M 13 Washington
U S Census, 1920 Maxfield, Thurston, WA
Citing this Record: "United States Census, 1920," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/MHF8-WY7 ), Elizabeth Thompson in household of C C Thompson, Maxfield, Thurston, Washington, United States; citing sheet 2A, family 33, NARA microfilm publication T625, FHL microfilm 1821942.
C C Thompson Head M 58 Iowa
Elizabeth Thompson Wife F 55 Oregon
A E Watkins Son M 35 Oregon
Mary Watkins Wife F 18 Washington