In 1910 Mary Hagen would be the mother of William Bright otherwise she would be called mother-in-law.
In 1930 Harold was still single aged 32 and lived in Wayn, Wooster, Ohio. He was an electrician at a battery plant. He was born in NY and his parents were born in NY.
World War I Draft Registration Cards, 1917-1918 Name: Harold Nelson Seely City: Mansfield, YMCA County: Richland State: Ohio Birth Date: 27 Aug 1897 Race: White Roll: 1851087 DraftBoard: 0 Age: 21 Occupation: laborer, Roderick Sears Mfg Co. Nearest Relative: Edward Suly (not sure on that)Sag Harbor, NY Height/Build:med/med Color of Eyes/Hair:blue/lt Signature: Harold Nelson Sealy
I believe this would be Harold in 1910: 1910 United States Federal Census Name: Harold Seely Age in 1910: 12 Estimated Birth Year: abt 1898 Birthplace: New York Relation to Head of House: Son Father's Name: Edward Father's Birth Place: New York Mother's Birth Place: New York Home in 1910: Southampton, Suffolk, New York Marital Status: Single Race: White Gender: Male Household Members: Name Age Edward Seely 43 Frank Seely 14 Harold Seely 12 William Seely 10
1920 United States Federal Census Name: Edward B Seely Home in 1920: Southampton, Suffolk, New York Age: 54 years Estimated Birth Year: abt 1866 Birthplace: New York Relation to Head of House: Head Spouse's Name: Ella Father's Birth Place: New York Mother's Birth Place: New York Marital Status: Married Race: White Sex: Male Home owned: Own Able to read: Yes Able to Write: Yes Image: 370 Household Members: Name Age Edward B Seely 54, dairy farmer, b NY Ella Seely 54 William Seely 23 Abbert Seely 15 Rooland Smith 28 Edward Smith 27
1920 census for Blanche Bright. She attended the College of Immaculate Conception, Mount Marie 1920 United States Federal Census Name: Blanche Bright Home in 1920: Perry, Stark, Ohio Age: 13 years Estimated Birth Year: abt 1907 Birthplace: Ohio Father's Birth Place: Ohio Mother's Birth Place: Ohio Marital Status: Single Race: White Sex: Female Able to read: Yes Able to Write: Yes Image: 611 Household Members: Name Age
Bright, Blanche, 13, student, b Niles, Ohio, par b Ohio
Ohio Deaths, 1908-1932, 1938-1944, and 1958-2002 Name: Blanche A Seely Birth Date: Est. 1906 Gender: Female Race: White Residence City: Canton Residence County: Stark Residence State: Ohio Residence Country: United States Death Date: 27 Apr 1976 Hospital of Death: Aultman Hospital City of Death: Canton County of Death: Stark Certificate: 031188 Age at Death: 70 Certifier: Physician Autopsy: No autopsy Marital Status: Widowed
In 1920 David and William Jr lived together in STark Co so neither of those is likely Blanches parent. Both were married and had no daughter with them. So I can't figure out who's daughter she was. Maybe on of the girls had her out of wedlock.