Injured player/Coach beckoned and more

[stripes2255]

JV girls game last night. Team A has six players in the book to start the game. Midway through the third quarter a girl who swings on the varsity team leaves the bench to join her varsity squad. The team is now left with the five that are on the court. Midway through the fourth quarter a player for Team A goes down with an apparent injury and the coach is beckoned on the court. Understanding that this injured player must be replaced, what is our recourse here? Play with four until the next dead ball? Ask that the sixth girl in the book to come and check in(although this would take some time since she wasn't around)? Tell the coach he must buy the injured girl back in with a TO?