your are right, it would have been too easy! And I sure your would have think about it.
Now Louis Ducharme, Laurent's brother, had only 2 sons from Marie-Françoise Jourdain-Labrosse:
1) Louis, the one that married Angélique Marchand in 1786. He died at St-Francois on Feb 22, 1789. I don't know if he has any children. Angélique married again in 1795, to Ignace Robitaille.
2) Pierre, born around 1765, married to Marie-Anne Delière-dit-Bonvouloir on Now 23, 1803, in Assomption church, Windsor, Ontario. He died in 1824, also in Windsor. I don't know if he had any children.