So, to resume:

There was a Lazzaro Antonio (we discover his 2nd name) married to Margherita Taravella.
They had Domenico Giacomo Q (grandfather of Sylvain), Luigi Lazzaro Q (great grandfather of Loris), Antonio Q and Andrea Q.

Domenico G. Q. married Maria Taravella 1876 from Rocca of Ferriere daughter of Marco Taravella and Francesca Mutti.

His brother, Luigi Lazzaro, married another Maria Taravella 1871. She had a sister (or half-sister?) named Rosa married with Patrick Q.