I watched the ballet section from AiP this evening and noticed that Saul Chaplin used the Mattchiche much more than Gershwin did in the original. Chaplin used it as a sort of motif everytime the pompiers double-timed through and they in turn seemed to be a sort of constant that appeared in every scene. Also, Hugh Fordin (in his book The World of Entertainment) says there are seven La Sorella in the piece by various composers. That's something I want to track down next.