Common sense and fair play. Pitch is thrown behind the batter and it hits the batting glove in the back pocket. Are we really going to keep the batter at home plate? No. We are not.
Starters:
Jones DH
Smith F1
Bench Player:
Thomas replaces Smith as pitcher in the 3rd inning.
In the 4th inning Jones hits a double and turned his ankle rounding 1B and needs to come out of the game.
Offense reenters Smith for Jones and remains in the game as DH for Thomas who continues to pitch.
Legal?
For the most part our sub varsity is wild west. Equipment is legal of course, but playing rules, pretty much whatever is decided. One of the best things we ever did was time limit the games thought. Nobody needs to see a JV game longer than 2 hrs.