Also expect to get a long and strongly-worded message from the parent of the girl you sent back to 2B about how...
1) You're treating her unfairly.
2) You're a terrible coach.
3) Your decision has ruined her chances to play college ball.
4) All of the above.
That's only for 12U. At 8U / 10U, they'll pull their kid off the team for not being "competitive". At 7U or younger, the parent will confront and threaten you physically.
At 14U, a few might grumble quietly. At 16U or above, several will applaud, and most won't even think anything negative.