No question about that.
As for FFC listing "Fat Clemenza" in the family chart shown at the Senate hearing:

If you can look closely at the chart (SC has posted it here many times, and it appears on p. 215 of Lebo's book), you'll see that FFC was having some fun with the names and identities he listed. For example, his father's photo appears over the name "Carmine Coranda, alias The Plunge." A young guy, looking suspiciously like FFC in a high school photo, is listed as "Francis Forducci, alias The Kid." The same photo, flopped and blurry, appears over the name, "Gaetano Sirillo." And "Salvatore Plumari's" alias is "Sally Pee."

Of course, "Fat Clemenza's" photo doesn't appear on the chart because Paramount and Richard Castellano couldn't come to terms. So, perhaps, FFC was taking a shot at the recalcitrant Castellano by listing him as "Fat Clemenza."