One of the lessons donors can learn from the uproar over "Three Cups of Tea" author Greg Mortenson is that a nonprofit needs more than three members on its board, especially when it is led by a charismatic leader who might have trouble separating personal business from the organization’s business. Mortenson’s nonprofit, the Central Asia Institute, has only three directors overseeing the charity, which is the minimum required by its home state of Montana, but not enough for an organization of that size, charity experts say.