I am not an authority on Welsh naming conventions, but from what I understand before they used last names a child's name was its given name then the son or daughter of the father. My name in Welsh would be Carol ferch (or verch) Vaughn. I am Carol and my father's first name was Vaughn therefore I am Carol the daughter of Vaughn. My first Vaughn ancestor was actually John Vaughan ap Llewellyn. When people began to use last names he became John Vaughan while others in the same family became the Llewellyns. Carol