Hi JC,
No relationship whatsoever to that family. It's just that I have compiled thousands of Leblanc marriages throughout the years.
Interestingly, you mentioned that a brother of the groom, Francois, was present, and I happen to have the following marriage:
- Francois LEBLANC (s/o Pierre & Catherine RENAUD dit LOCAS) married to Adelaide LABELLE (d/o Louis & Marie MARCOTTE), January 26, 1829, in St. Vincent de Paul, Laval.
This not to say that Pierre is necessarily the brother of Francois, but at least it's worth investigating.
Mario