I was told that "subs are allowed only after the first shot when shooting two free-throws". Is this true and if so where is it stated? I have a NFHS B-Ball Officials Manual and cannot find this mechanic. Maybe an oversight.

Case Book 3.3.1D (b)A7 and A8 must wait until prior to the last remaining freethrow to enter the game

Why is this so? What advantage/disadvantage is gain?

...only if you have a kid foul out...
 

The rule book states to allow subs before the last try of mulitiple throws, or before the one shot on a 3 point play. The exception to this is in a case where you have a kid foul out, you can let any subs that are at the table into the game since you already have a delay to get a sub for the player with 5 fouls.

The logic...
 

The rule exists because some coaches send substitutes to the table in a "staggered" time manner. If officials were required to call the subs on the court prior to the first attempt they would often times be beckoning subs twice as much.

As mentioned by Jeremy Hohn, subs should be beckoned prior to the LAST FT, OR when replacement of a disqualified player is required (most often 5th foul DQ).

The NFHS/NCAA rule applies to multiple free-throws that are the result of a PERSONAL foul. If part of the penalty for a personal foul is two or three free throws, no substitutes can enter until just before the last free throw if the group. The exceptions are: (1) If a player must be substituted because of disqualification or injury, that player must be subsituted and if there are other substitutes waiting to enter they can enter after the substitute of the disqualified or injured player has entered; (2) If a team request for a timeout is granted before the free-throws are shot and substitutes are waiting to enter, they can enter at that time.

It's a time saving measure. Rather than bring in subs immediately before the first shot, and then again aftet the second shot, bring them all in after the first shot. Nothing is gained by bringing them in before the first shot, just lost time.

Now I understand!! I thought it was allowed as long as the ball wasn't administered to the free thrower.

I love being a Ref, you learn or experience something new every game.
Thanks!!