[Ref in PA]

6-4-4 "The direction of the possesion arrow is reversed immediately after an alternating-possession throw-in ends or when the throw-in team violates."

6-4-5 "The opportunity to make an alternating-possession throw-in is lost if the throw-in team violates. ..."

In the original play, B1 commits a violation by breaking the plane (9-2-11). The violation penalty is to record the action in the book. The ensuing throw-in by team A is a spot throw-in as a result of the violation by B1 (see the penalty for section 2). In addition, there are special penalties for the boundary violation by B1 (the penalties include instructions for multiple plane violations, dislodging the ball, fouling the thrower).

Therefore, at the end of it all, A retains the arrow.

Next there was some discussion about A1 throwing to A2 who has his foot touching oob. In this case, A2 violated according to 9-2-10. Even though the throw-in did not complete, the throw-in team violated (9-2 is all about throw-in violations). In this case the arrow is switched to B.