the rizzuto clan is not just part of the montreal mafia but also a group of intermarried families who can trace roots back to sicily and more specific to cattolica eraclea, the hometown of the rizzuto family.
at this point in time leonardo rizzuto is considered the boss of this clan and a overall boss of the rizzuto-sollecito faction of the mtl mafia along with stefano sollecito.
however i would say that only a small part of the rizzuto clan can actually be said to be involved in criminal activity within the wider montreal mafia. in this respect then L. rizzuto is the point of contact for families with last names; cuntrera, renda, spagnolo, manno, cammalleri, ragusa, sciortino etc. if and when problems arise.

as for the actual definition of the rizzuto-sollecito faction of the mtl mafia in the context of the cosa nostra it is an independent group of allied mafia clans. the mafia in montreal is not unified with a typical admin set up. decades of constant warfare and arrests have fractured a once unified crime family. the rizzuto-sollecito faction is an alliance of two powerful clans (rizzuto,sollecito) that is also allied with the barberio-pizzi clan to control large parts of criminal activity in montreal and surrounding areas.