Fredo was also a bit tipsy when he met Kay for the first time at Connie's wedding.

And Pentangelli seems to have had a few too many at Anthony's communion party, as he knocks over a glass of vino at dinner (Mike to Neri: "The old man had too much wine").

And if you want to bring the book into the discussion, Johnny's pal Nino Valenti ultimately drinks himself to death (while Captain McCluskey refrains from wine at his last supper, commenting to Sollozzo that "I must be the only Irishman that don't take the booze.")