I looked at what I have and I do not see a William. I do have to say that the name "William" is not one used too much in Sicily, so It was probably changes at some point.
Frank Capra's parents were Salvatore Capra and Rosaria Nicolosi. Does that fit? Accordint to what I have, their children were: Benedetto ( named after the paternal grandfather) Antonino, Luigia, Ignazia, Anna, Giuseppe Antonino, and Francesco (Frank Capra). Let me know if y9ou need more info.