Name Changed by Deed

I'm wondering what's the correct way to put my father-in-law in our family tree as he changed his surname by deed ? His mother died at childbirth & Tom was brought up by his father's sister in the Owers family. His surname was Williams from birth but when he got married he decided to change his name by deed to Owers. Do I put Williams/Owers in our family tree or some other way? Any help with this would be appreciated.