Bonjour et merci pour la réponse, Danielle. Thank you for edits. I hadn't caught up to my findings yet.
I understand that she or her parents might have chosen to call her Marie rather than Madeleine (the name her godmother Madeleine Leroux gave her, I'm guessing). But since there's no actual evidence, no link, I'll note that Madeleine being Marie is possible but not certain. She can't be any of the other daughters her parents had, so maybe even probable.
The copy of the marriage contract I have has only the names of the couple, not the parents. The act of marriage does not call her a minor, so hopefully that suggests that she was 21 or older.
I know that the age on a burial record is not necessarily reliable. When I looked at the St-Charles registry for 1750, I found only the burial of an anonymous newborn. wonder when she went all the way upriver to Montréal. After the 1802 marriage of her son François, I guess. I haven't seen this kind of movement before.
If the profile (with some final corrections) is solid enough for you, then I'll do final edits and be done with it for now.