Nobody has been able to explain how one bullet could do all the things it would have to have done either.
Years later Gerald Ford admitted changing some of the trajectory detail to make that theory work.
To be honest, I don't remember the particulars associated with that since it's been awhile.
Actually, they found out how the single bullet did it's work. They mapped out Dealy Plaza and used computer drawings to show the trajectory. Pretty simplistic. They also tracked the bullet to it's origin. It was within a nine foot diameter of the sixth floor window.