The remainder of Vaughn's Brigade was in East Tennessee, not Georgia. For instance, reports of General Morgan's death at Greeneville TN include that command, along with the 16th Georgia Partisan Ranger Battalion.

Since it took place near home counties of the battalion, The action at King's Tanyard could have involved a few members of this command, gone home on furlough or detailed in search of horses.
http://www.waymarking.com/waymarks/WM7PNK_Battle_of_Kings_Tanyard_GHM_007_3_Barrow_Co_GA