Thread has gotten more interesting than I would have thought.

Adjustment to the OP:

B3 shoves (not hard or deliberate) A2 on the way to the shooter A1. A1 is hit by A2 in the act of shooting.

Just so we are on the same page. The foul is on B3 but it isn't a shooting foul because B3 fouled A2. So it is on the floor and we have A's ball OOB unless bonus is in play.

In this play, there are a few things to consider.

First, I'm giving A2 a lot of benefit of the doubt on whether the try had started so I can count the basket if it goes in.

I'm also thinking long and hard about an intentional foul unless B3 trips or something and it's purely accidental.

Ideally, the basket goes in and we penalize the foul accordingly.