Joseph RIVARD baptised October 3, 1736 in Champlain was buried March 3, 1782 at Yamachiche Qc (aged 44), a celibate. So he can't be the Joseph RIVARD who settled in St.Louis MO.
On June 23, 1767 (Duclos notary), Antoine RIVARD Sr., widow of Josephte TROTTIER, from Batiscan splits the estate of his deceased wife between his living children : Francois-Xavier, Jean-Baptiste, Charles, Joseph and Antoine. Two of those children : Antoine and Joseph, are absents, being in « les Pays d'en Hots ». Antoine Sr. then elects curators to manage the assets of his two absent sons.
We know that one of the absent sons, Antoine RIVARD Jr, married July 08, 1767 in Sandwich (now Windsor, Essex co., ONT) to Felicite STE-MARIE and his descendants have settled in the Windsor / Detroit area.
The only other son who’s fate is unknown is Joseph. His declaration of June 1787 in the Benito Vasquez affair fits.
The other sons have all married and settled either in Batiscan or nearby parishes in Quebec.
I believe that the Joseph RIVARD who signed a hiring contract with Alexis LeMoine Moniere to go in the Illinois on May 28, 1753 (Hodiesne notary) was born c. 1727 in Batiscan or Grondines, to Antoine RIVARD dit LAVIGNE and Marie-Josephte TROTTIER. In the 28 May, 1753 contract, Joseph RIVARD is said to be from Batiscan, Qc (Batiscan is in Trois-Rivieres judicial district). His baptism record is lost, but the fact his father names him in the June 23, 1767 contract proves his existence.