[Upward ref]

I guess my understanding hinges on team control for this sit.,
1) even though b deflected the pass into the backcourt,team control is still with a ?
2) If the ball hits the floor (in the backcourt after b's deflection) then b caused backcourt status?
3) if the ball doesnt hit the floor (in the backcourt after b's deflection) and a is the first to touch, b didnt cause the backcourt status ??
4) didnt b's deflection make him the last to touch ?
is 4-12-4 the main emphasis ?