Indeed, Cuthbert'S origin is not clear. Laurent Ducharme and Marguerite Métivier had 6 children, as far as I know. Of these, 4 sons: Louis (he died the day of his birth), Joseph-Laurent, and Louis and Pierre-Augustin (twins). Also 2 daughters: Marie-Marguerite and Madeleine-Marie.
No Jean-Marie among them. But it not impossible that they had a som with that name, or that the one who wrote about Cuthbert made a mistake about his parents.
Do you know when and where Laurent Ducharme and Marguerite Métivier, and who their sons married?