I sure hope that you succeed in locating Paul's father. This must be very difficult for you. Have you tried the People Search on Yahoo? Here is the URL: http://people.yahoo.com/http://people.yahoo.com/ I typed in Frank Defazio and put MA in the state, and there were two listings. For White Pages listings, you can also look on this website:http://www.switchboard.com/http://www.switchboard.com/
I also looked in the Social Security Death Index, and I could not find a Frank Defazio with the birth year of 1937. You can look on the Social Security listing, too: http://ssdi.genealogy.rootsweb.com/http://ssdi.genealogy.rootsweb.com/and just follow the instructions on the screen. (If someone dies who has never received any benefits, they may not be on this listing.)
Was he called Frank and named Francis? If so, you must look under both names.
Just wanted to give you some suggestions. Perhaps you have already tried these. Anyway, good luck in your search. It would be nice for your kids to know their grandfather.
P.S. Please don't take offense at this suggestion, but if you type your message in both upper- and lowercase, it is a lot easier for the rest of us to read. Just a suggestion.