Old test question

[Scrapper1]

While studying for this year's test, I came across this situation and I'm not sure if I'm misunderstanding the rule, or if I'm reading the question wrong, or what. So I'm asking for opinions.

A1 is fouled by B1 and is awarded 2 free throws. The foul is B1's 5th personal foul. The official notifies Coach B of the disqualification and starts the 20-second replacement period. A6 and A7 report to the scorer's table before Coach B replaces B1. The official beckons A6 and A7 into the game.

The answer key says that the officials were correct.

Now. . . I was always taught that NOTHING happens until we get a sub for a player who must be replaced. But it sounds like in this question, they're saying that you can bring in any subs who have legally reported, even before the sub for the DQ'd player comes into the game. Is that correct?

Am I mis-reading something? And by the way, (apparently) this question or some version of it has appeared on several recent tests and is always answered the same way, so it's not a one-time mistake in the answer key.

[ga314ref]

See 3-3-1(c) Exception. Once the coach is notified of B1's fifth foul, he's bench personal and while the coach has 20 seconds to replace him, the other subs don't have to wait until that replacement enters the game. After the replacement is beckoned, no other subs may enter (See the 3-3-1(c) Exception example in the "Simplified & Illustrated, also known as "the comic book") before the the last free throw of the series.