Spacing for defense?

[representing]

Originally Posted by BillyMac

Teammates shall not occupy adjacent positions which are parallel
to and within 3 feet of the boundary line if an opponent desires one of the
positions.

So if A1 is taking the ball out of bounds and A2-A5 are standing shoulder to shoulder as per above (parallel to and within 3 feet of OOB line) and B1 wants to get in between A2 and A3, you have to let them? When does this have to take place, before you give the ball to A1?

EDIT: another question... what if B1 and B2 wants to get in between A2 and A3? Is it only allowing one opponent in between any two players, or can as many opponents request to get in between any two players?