(ABT 1828-)
| +---James Trethewy 
| +---James Trethewy (ABT 1681-)
| +---William Trethewy (ABT 1714-)
| | | +---Theophilus Coad
| | +---Grace Coad
| +---William Trethewy
| | +---Margaret Lang
| +---William Trethewy (ABT 1773-)
| | +---Mary ?
+---Ann Trethewy (ABT 1803-)
+---Philippa ?