Oh, I suppose I should have been more clear - I didn't mean you had to add a whole new control point. All you need to do is make sure that the name of the control point to capture and the name in the trigger match. If these two things ever DON'T match, the cart won't move.
So, that key should always point to the next control point in the cart path. That's why, if you look at the outputs tab of your new cp_one, you'll see it tries to update the trigger's control point to the next one upon capture.
Hopefully that made sense.