Assignment as a son of Vivian Quisenberry/Quesenberry and Sally Wright is based on the fact that in the 1900 census, Anna B. Quesenberry, widow of Vivian Quesenberry Jr., is living with George Oscar Quesenberry, with the relationship recorded as aunt. That would mean that Anna’s husband Vivian Jr. was a brother of George Oscar’s father.

1860 census of Rappahannock Co., Virginia, Woodville P.O., (page not dated), lists on p. 3 as family #18:
Benj Quesenberry, 36, no occupation; Elizabeth, 37; George, 33, merchant. C. H. Thompson, 25, merchant. All born in Virginia.

The preceding household is that of John W. Miller with wife Mary, including daughter Melvina who would shortly after this census marry George Quesenberry.

The register of appointments of U. S. Postmasters for Rappahannock Co., Virginia records as successive postmasters of Slate Mills:

George Quisenberry, appointed 21 Apr 1858
James Walter, appointed 3 Jan 1865
James W. Popham, appointed 12 Jan 1866
Mrs. Mell A. Quisenberry, appointed 27 Sep 1866

In 1870 Melvina, apparently widowed, and son George are living with her parents:

1870 census of Rappahannock Co., Virginia, Stonewall township, enumerated 15 July, lists on p. 25 as family #172:
Miller, John W., 61, farmer; Mary, 60; Catherine, 25; Cora, 22; Oscar D., 22, farm laborer; Fannie, 19. Quisenberry, Melvina, 30, school teacher; George, 7. All born in Virginia.