Masseria went to Chicago to enlist Capone's help. In return, he promised Capone (a Neapolitan) help with the Sicilians who were running the local Mafia, then called the Unione Siciliano, under the leadership of Joe Aiello, a Capone foe. You're right: Magaddino was Bonanno's cousin. He saved young Joe's life by defending him in a sit-down over a territory dispute long before Joe became Don. His help to Maranzano was offered because Magaddino, like Maranzano, was a Castellemmarese. Later Magaddino and Bonanno became enemies. Magaddino pressured the Commission to remove Bonanno as the head of his own family. Bonanno says Magaddino kidnapped him in 1965. Others say Bonanno did his own disappearing act to escape Federal warrants and Commission assassins.