Take a look at how voting agreements work with mergers.
If a majority of the shareholders (MM and C that have 66 2/3rd of the voting rights) agree to vote a certain way there will not even be a proxy for the other shareholders to vote on (you get what is called an "information circular"). There isnt even a shareholder meeting required!
Not only do they have a majority of the board seats, they also have a majority of the voting rights!