Robin, Cornelius was a Brandon genetically. He belongs to Linage 2 - meaning that his YDNA differs slightly from those of us that are Linage 1. He was probably a more distant Brandon cousin than some. He came to Rutherford County, Tennessee with George Brandon (my GGG grandfather) about 1800 - 1807. None of the Brandon family I have examined were Tories.
Sidney is my 4G Grandaunt and married your James 1772. Sidney did file for divorce on about 1798 because James killed a unknown Branson/Brandon during the war. No one that I am aware of knows who that might have been. Maybe related or not.