Combination Question

[rainmaker]

Case Book 2.10.1A. Play: A1 is fouled but erroneously is not awarded two free throws even though the automatic bonus is in effect. Team A is given a throw-in, and A1 inbounds the ball to A2 who is tied up by B1 resulting in a held-ball situation. The error is discovered following the held-ball call. The possession arrow is pointing to: (a) A's; or (b) B's basket. Ruling: In (a), the merited free throws will be awarded, and play will continue from that action, since Team A had not lost possession between the error and when the error was recognized. However, in (b), the lane is cleared for A1's merited free throws, and play resumes from the point of interruption which is an alternating-possession throw-in by Team B.

My question: I'm assuming the arrow is reversed? When? What if, in (a) there is a foul during the throw-in by B? or in (b) by Team A?

In (b), how do you explain to coach A that B committed the foul, but B gets the ball, especially if A misses both shots?