Ciao sonson, you are looking for the people who lost their home in Fabbriche di Careggine, not in Vagli Sotto.
Fabbriche di Careggine was a little village whose inhabitants were obliged to leave it in the '50 of the last century as it was decided to create a dike there. It was at that time that was create Vagli Sotto lake. Fabbriche di Careggine was near Vagli Sotto, but the municipality was Careggine.
The people who lived there emigrated from Fabbriche di Careggine who is now known as the ghost village who reapper every 10 years when the lake needs to be cleaned. ( sorry for my english ).
Your grang mother, Lucrezia Fazzani was born in Roggio, a little village near Vagli Sotto.
Many families left when Fabbriche di Careggine (Vagli Sotto) was flooded. I know some went to Argentina (not sure who) and a few families eventually ended up in Yellowknife, Northwest Territories, Canada. There was hard rock gold mining that seemed to be the reason some of the town's men first went there. I do not have all the names of these men or the families that eventually followed but here are some: Franceschi, Franchi, Bertolini, Fortini, Baisi. I am sure there are more. I am researching these names and would love any help.