You tell us Roscoe. What physical law am I missing that says that the aircraft's ground track cannot be altered or that the heading cannot be held constant when applying the control inputs to enter a slip? Because if you don't turn the nose off the initial heading your ground track is not going to remain the same. How about the opposite. You are on final in a crosswind, left aileron, right rudder, tracking the centerline of the runway. You are in a slip, correct? So neutralize the controls, nose still pointed down the runway. Isn't your ground track now going to change as the crosswind causes you to drift to the right of the runway? What is it that you two aren't getting here? This is basic stuff.