Maybe you already know this, so just for the benefit of other researchers :

Thomas GAREAU (son of Bernard Gareau & Suzanne Mornay) was married three times :

1st m. 08 Feb. 1773 L'Assomption (L'Assomption co.) Quebec
BRIEN dit DESROCHERS, Archange (Louis & Josephte Senecal)

2nd 01 June 1790 St.Roch de l'Achigan (L'Assomption co.)
BERTRAND dite CARON, Marie-Judith (Joseph & Marie Degré dit Langevin)*

3rd 26 Oct. 1801 St.Roch de l'Achigan
RITCHOT, Marie-Anne (Pierre-Louis & Marie Claire Lefebvre) widow of Joachim Lemyre dit Marsolais

* In the marriage record, Judith Bertrand's parents are named Francois Bertrand and Marie Langlois. However, this is an error made by the parish priest. According to her marriage contract, Judith' parents (who are not named, as her deceased father is represented by her uncle Francois Bertrand and his second wife Marie-Ursule Labrie) are Joseph Bertrand and Marie-Josephte Degré dit Langevin, married 07 Jan. 1768 at St-Antoine de La Baie du Febvre.

Feel free to contact me for more details on this case.