Question

what does James Madison have to do with the constitutional convention

Answer 1

Madison more or less wrote the Constitution.

Answer 2

so what does Alexander Hamilton, Benjamin Franklin,and William Paterson got to do with it

Answer 3

I didn't say Madison wrote the Constitution himself. His was merely the framing vision, and quite a number of compromises were effected to get it implemented, in which the people you mentioned had much to do.