[BoomerSooner]

Typically the way I've handled this and seen it handled is that throwing with another player during a dead ball is never an issue as long as they are ready to go once the game is ready to resume.

The only catch to this is that if the pitcher is throwing with the catcher at the start of the inning (prior to the first batter), then I'm having my partner count the pitches and once I'm done talking with the coach about the substitutions, I'm allowing at least 1 more throws (so the catcher can throw down to 2nd base, infield can get the balls off the field, etc.) while I get back into position and ready to resume play. If the pitcher is throwing with F5 while waiting for me to return in this situation, then my assumption is that the pitcher is ready to go already. The only exception would be a situation where the delay is for the substitution of the catcher, and the team didn't have anyone else available to warm up the pitcher. As much as the delay stinks, I'm still allowing the full allotment of warm-up pitches without regard to the number of throws the pitcher made to F5.