You are absolutely right.
In fact, Mary's last name is Villiot dit Latour but year by year we have lost the Villiot part. And there is more: we find Villiot, Villiotte, Veillot, Veillotte. In my family, it was Villiot dit Latour. Sometimes, it's quite confusing.
Thanks again for your help! And if on your part, you need informations concerning Canada, just let me know!