When exactly is a free thrower allowed to cross the line. Is it as soon as it hits the rim they can cross the line.

Also what if on a free throw A1 who is shooting the free throw crosses the line but so B1 also commits a lane violation is the free throw just terminated.

High school = enter when the ball hits the backboard or rim.

College and pros = enter on the release.

In your play, both players have violated. Go to the AP arrow.