Hi,
Ancestry is always a big help with research. You can get SSDI index to find out where relatives died and usually their death date. You have to be creative with names when you find a dead end. Also another good site is www.familysearch.org. Do not believe all the facts on that site until you research another source. Go to that site, and go to prototype and type in Vergino Mello and Massachusetts, United States that will pull up Vergino and Margarida's marriage certificate. It also lists their parents names. If you live in MA, your library might have access to Boston Public Library death indexes.

I will try to find out if his siblings are still alive or who their descendents are.

Good Luck!
Carol