You say that you had thought Marie Mathurine DUPONT was the dau. of François GUILLEMOT dit Lalande and Madeleine DUPONT.
Normally, if she had been their dau. she would be a GUILLEMOT dit Lalande, not a DUPONT.
None of the ten children listed by Jetté for the couple François GUILLEMOT dit Lalande and Madeleine DUPONT and born in the Montreal area between 1686 and 1700 seems to have been baptized "Marie Mathurine". Their dau. were baptized Françoise-Madeleine, Madeleine-Louise, Marie-Chrétienne, Marie-Catherine and Geneviève-Angélique.
I find a Mathurin (masc.), born to Olivier GUILLEMOT dit LeBreton and Jeanne CAUCHON in 1690. That Mathurin GUILLEMOT was married to Marie-Angélique MARET in 1709; they had 8 children, but no Mathurine (they had Marie-Angélique, Marie-Madeleibe and Marie-Catherine).
I also find one Marie GUILLEMOT born to Jacques GUILLEMOT dit Lalande (son of François and Madeleine DUPONT) in Kaskakia in 1717.
I find no trace at all of any Marie Mathurine DUPONT.
Nor of Antoine François AUFRERE. In fact, I find no Aufrere at all in New France up to 1799. Are you sure of the spelling? Do you have thne date-place of his marriage to Marie Mathurine DUPONT ?