His oldest brother, Willis Perry Bocock (1807-1887), may have been the most successful lawyer in the area (Buckingham County splitting off Appomattox county in 1845), as well as state attorney general beginning in 1852. Although Thomas' legal mentor, Willis resigned his official position and moved to Marengo County, Alabama in 1857 shortly after marrying Mourning Smith, a wealthy widow originally from South Carolina, although returning for family visits. Another elder brother, John Holmes Bocock, became a Presbyterian minister in Lynchburg and then the District of Columbia. A slightly younger brother, Henry Flood Bocock (b. 1817), also became a lawyer, clerk of the Appomattox County courthouse (at the time of Lee's surrender to Grant), director of Farmer's Bank in Lynchburg, as well as Presbyterian lay leader and later trustee of Hampden-Sydney College. Their brothers William Stevens Bocock, Charles Thomas Bocock, and Nicholas Flood married but did not have such distinguished careers, and Milton Bocock died as a teenager; their sisters Amanda, Martha, Mary Matson and Mary Fuquar all married.