Nick Gentile said this about Al Capone and his entry into the Cosa Nostra sphere (this is from the translated manuscript of Gentile´s autobiography "Vita Di Capomafia":

"Tony Lombardo [the head of the Sicilian Mafia in Chicago at the time], a man of goodness and tremendous ability, alert and always remembering my counsel and the principles of the Mafia, having learned that Joe Masseria was making Al Capone pay a contribution of about $50,000 because he was not part of the Mafia, requested him not to pay the sum. The Governo Central [Control Government, the assembly of the most powerful bosses at the time] having found out the action of Tony Lombardo, called Al Capone to New York. They explained to him the organisation of the Mafia and conceded to him the privilage of becoming part of the family. [Most likely Gentile meant to say "part of the Mafia".] They elected him "Capo di decina" (head of ten) with the authority to select trustworthy youths. That ten, even though they operated in Chicago, were to be subject to the family of New York whose Capo (head) was Joe Masseria. All this was granted him with the condition that he would eliminate Lombardo and [Joe] Aiello. And they also gave him the authority to eliminate anyone else whom he disliked. [I understand this last part to mean that Capone was given the authority from the Cosa Nostra bosses to get rid of anyone within the Chicago Mafia without having to ask for permission.]"

It´s not always easy to understand Gentile, and there may be vital information lost in the translation (those of you who have read the manuscript or the book may agree) but if Gentile is right, this means that Capone was connected to Masseria but was given power to handle stuff in Chicago as it pleased him. Gentile never mentions Capone being made though. After the Castellammarese war and after the elimination of Masseria, the new boss of bosses Salvatore Maranzano, recognized Capone´s group as a Cosa Nostra Family, most likely as a way to reach agreement for peace, because Capone had fought on Masseria´s side.