Mass sub match-ups execution

[Amesman]

Good game last night, a couple of competitive girls soph squads -- with coaches working for every angle at every opportunity. A couple of execution questions for the collective wisdom here, please.

Team B subs all 5 players who will now be facing Team A's full-court press. I'm administering the throw-in on the endline and partner tweets, beckons me in a state of confusion to near the division line and says Coach A wants a defensive match-up.

Partner's unclear on what's being asked but I realize since it's three or more, this match-up can be requested. So the question: What's the best way of conducting this? Only Coach A and I know what's going on at first so it isn't about to come together too quickly.

First, I told my partner he's entitled to this, put some air in the whistle and beckoned all (confused) players to the division line, called over to Coach B to let him know what was going on and asked the players to face off.

But even then: Do we instruct them to stand five on one side of the division line, allowing the defense to pick and choose someone to guard?

Besides location, how long do we allow for this? It took about 15 seconds but I could envision some coach could try to stretch it. Just wondering.

The varsity guys in the locker room after my game tried to joke it off as merely a "courtesy" and didn't have much guidance for me when I asked them.

Oh yeah, sitch 2: Found out why it's really a good idea to let the game horn speak for itself, though I've seen the discussions here about whether to whistle a half dead, etc.

Two-point game ends on a contested rebound with one girl tumbling to the ground (twisted ankle, no contact). My whistle and raised hand/waving off to signify the end of the game momentarily confused a few folks who thought we might be shooting free throws. Don't know if I picked up a bad habit or what.