From the desk of Stephen White....
Firmin Landry is one of those ancestors who somehow seems to encourage people to long discussions, and even occasional disputes. I have checked what you have forwarded, and it basically agrees with what I have, although in so doing I found one place in the manuscript of the DGFA where I had forgotten to correct Firmin's age at death. Later on, I will check the typed version.
Karen’s theory about the Élisabeth who was listed with Firmin in 1763 being his sister, rather than his wife, is interesting. I do not know quite what to think about it, however. I can explain, however, why everyone has presumed that the Élisabeth in the census was his wife. It is because of the structure of the listing. In most censuses the head of the household comes first, followed by his wife, if the household head was a man and he had one, then come the children, if any, and then other relatives, such as unmarried siblings of the household head or his spouse, then come other in-laws, cousins, and orphans, if asny made up part of the household. So we presume that Élisabeth was Firmin's wife because her name follows his and comes before the names of his children. Now, the fact that Firmin's first wife is everywhere else called Françoise is a problem. It is possible, consequently, that this Élisabeth was not really his first wife Françoise Thibodeau. Maybe she was a second wife about whom we know nothing else. I do not recall offhand whether the record of Firmin's second marriage precludes this possibility by specifying that he was the widower of Françoise Thibodeau. The real problem is that none of these records should be taken to be flawless. The name Élisabeth for Firmin's wife in the census might simply be an error. The omission of his sister from the same census might also have been an error, if she had indeed been so omitted, although I think that if she checks the 1763 census again she will find that Élisabeth does appear at Oxford, along with her mother and sisters in the household headed by Olivier Babin.