Tom Day wasn't related to Jefferson A Day. Nor to Joseph Day or Washington Hudson.
His parents (Richard Day & Sarah Duncan) moved back to Fayette co IL before the 1870 census. Some of their children who had also moved to Collin co, went back to IL. His brothers, Willis & William served in a TX Confederate unit during Civil War.
His sister Lucy & husband Wm. Lansford were in Collin co in 1860; went back to IL. His brother, George, was in Collin co in 1860; went back to IL.
His sister, Francis Julia, married Benjamin Watson in Collin co. Stayed in TX for awhile; died OK.
His sister, Elizabeth, married George Howell in Collin co TX; stayed in TX for awhile, but died in OK.
The Day family was from Stokes co NC, moved to Logan co KY. Father, Henry, died in Logan co KY about 1821. His widow, Hannah Graham, and most of their children moved to IL. The Day family had close ties to the Graham family & Duncan family in KY & IL.