hi Lynn, Marie Langlois' mother's name is unknown, it could easily have been Leblanc, or else they are not first cousins but second cousins, see a lot of those being simply listed as ''cousin'' without specification.
Marie's first marriage was in France, it hasn't been found even. Her second marriage only lists her as widow of her first husband.
The link you give is for Marie, it gives its sources, which are basically the same as we already have.