With that one clue,
I searched in data banks for the marriage of a Léo Lagacé.
What I found was his first marriage.
That was quite a shock.
My grandfather was married in 1912 and I believe no one knew about it at the time. With this info I had his parents’ names: Henriette Alexandre and Stanislas Lagacé.
Someone sent the image of the marriage taken from the parish register of Saint-Hyacinthe-le-Confesseur.
There I found out that my great-grandfather was still living but that my great-grandmother was dead. Stanislas was a contractor living in Bristol, Connecticut, and he did not attend Léo’s marriage.
I found who were the parents of Stanislas Lagacé and Henriette Alexandre by using data banks.
I could then link Stanislas Lagacé with the first Lagacé: André Mignier.