Kevin
I'll take a stab. I believe the CR is attached to the position, not the player. If that is true, the same girl could be CR for the pitcher, whoever the pitcher may be at a given point in the game.
The same girl cannot be CR for the pitcher and the catcher, and if the CR subsequently enters the game as a "regular" player, she is no longer eligible to be a CR.
Finally, a player may not be a CR and enter as a batter in the same half inning. She could, however, be a CR in the top of an inning, and enter the game as a regular defensive player in the bottom of that inning.
I'll take a stab. I believe the CR is attached to the position, not the player. If that is true, the same girl could be CR for the pitcher, whoever the pitcher may be at a given point in the game.
The same girl cannot be CR for the pitcher and the catcher, and if the CR subsequently enters the game as a "regular" player, she is no longer eligible to be a CR.
Finally, a player may not be a CR and enter as a batter in the same half inning. She could, however, be a CR in the top of an inning, and enter the game as a regular defensive player in the bottom of that inning.