Coach sits... or not
 

Federation Rules - Between sets 1 and 2, the R1 observes the libero and one of her teammates pulling off their uniform tops to switch from being libero to team member and vice versa. The R1 gives a yellow card to both players. Since the players were standing in the bench area when they pulled off their uniform top, does this mean that team’s coach can no longer stand for the rest of the match? In other words, would the coach also get carded? The bottom line is... are the players considered BENCH PERSONNEL between sets?

coach is warned
 

12.2.1 Situation A:
At the end of the warm ups, Team S players go to their bench and remove their warm up shirts to change into uniform tops. The referees ignore the incident. Ruling: Incorrect procedure. Comment: Removing any part of the uniform outside the dressing room or other private area shall be dealt with by the referee with a warning to the coach. State associations may have specific policies regarding removal of uniforms in the competition area.

However, what constitutes a warning? If a verbal warning to the coach is given, then no they don't have to sit as no sanction was given. If you define a warning as a sanction, then yes, the coach must sit if you apply the sanction.

That's one of those "in the spirit" type situations, imo, so I'd have given a verbal warning/reminder to the head coach. Though if a sanction is the appropriate reprimanding based off of rules and/or interpretations from the higher ups, then so be it; issue the sanction.

I'm not super involved in NFHS so I'm not sure what other (official) interpretations of that rule would be.

I had a similar situation at a freshman match recently. I just warned the coach that she needed to go to the locker room to change and couldn't change on the bench. I did not issue a card to the player. I actually did not see what happened because I turned away as soon as I knew what was going on. The comment from the JV player on the table was " It wouldn't be an issue if she had a sports bra on." I didn't need to be accused of looking at that, so I kept turned away till the team broke the huddle and then I warned the coach. I did not feel it deserved a card. There were bigger fish to fry like my repeated times having to come from the stand over to check lineups and correct servers for both teams. (We work freshman with 1 official).