(ABT 1517-ABT 1573)
+---Thomas Trethewy (-ABT 1616)
+---Bartholomew Trethewy
+---Bartholomew Trethewy (-1666)
+---Bartholomew Trethewy
+---Thomas Trethewy (ABT 1675-MAY 1743)
| +---Jane Bruart 
+---William Trethewy (ABT 1712-JAN 1777)
| | +---Phillip Mellow (ABT 1660-JAN 1711)
| +---Joan Mellow (ABT 1680-)
| +---Jane ?
Grace Trethewy (ABT 1745-BEF 1777)
+---Grace Rickard