[Ref in PA]

The technical foul penalty summary in the NFHS book on page 73 indicates that the substitutes are bench personnel and an indirect goes to the HC. I would also assume that a T is given for each player running on the court. In this case you would have to identify the players who came on the court, each would get a T and the HC gets an indirect for each T. If you call 3 Ts, that would be 3 indirects and the HC is gone.

Personally, I would find some way of making the subs go back to the table and doing it all over again. I would also give a short explanation to both coaches about why I am doing the substitution this way with the possible consequences that were averted by doing it over. It reminds the coaches to have better control over their players.