A convenient omission, Oli, although Michael, at his party, told Vincent that "Mr. Joe Zasa now owns what used to be the Corleone Family business in New York." A bit earlier, before Vincent joined them, Michael told Zasa: Joe, your business is your business. I have no interests or percentage – I’m out." So, it is arguable that Michael didn't care who succeeded Zasa.
A more serious omission: Who took over the Corleone Family, which was still under Michael's control in II, after Pentangeli flipped and the Rosato brothers were on the run?