(-JUL 1733)
+---Richard Trethewy (ABT 1720-)
| +---Isabel Beaubery 
(-FEB 1732)
+---Robert Trethewy (ABT 1759-)
| +---Ann Jewell
+---William Trethewy (ABT 1790-BEF 1851)
| +---Elizabeth Sarah
Thomas Trethewy (ABT 1821-)
| +---Nicholas Daddow
+---Grace Daddow (ABT 1795-)
+---Mary Nancarrow