The short, sweet answer is advice I got from a mentor: talk it out until you're all happy. But I would caution against joining a company with founders who want to be involved "but have no distinct role in its next phase." If as CEO you're helping the company to grow and creating a lot of value, you may come to resent the fact that you only got 1/3 (or 1/4) of the pie. Clearly defined job descriptions (and a new vesting schedule with a cliff for the original founders) can ensure that everybody stays hungry and works hard to make the company profitable.