‌Guillem Ap and Gwenlian Verch were married in a religious ceremony about 1360 in Of Cefnyddwyglwyd, Monmouthshire, England.  They had seven sons and four daughters, named John Ap, David Ap, Howel Ap, Howell, Thomas Ap Guillem, David Vychane, Philip, Jane Verch, Gwladis Verch, Gwenllian Verch and Janet Verch.