One of the most difficult things in sports, IMHO, is to hit a good to excellent pitcher in fastpitch, therefore I have always enjoyed seeing the runner on second signaling a batter, and the girls on the bench yelling out the catchers position, if the pitchers team or players on the bench were to attempt to break a batters concentration by waving their arms or intentionally screaming at her in the box, it would certainly be construed by some as unsportsmanlike behavior.
If you are allowing your players on second to interfere with the batters concentration and setting them up to look for one particular pitch you are simply making it easier for the pitcher and catcher.
I am certain any number of you will claim that your daughter or the batters you coach or teach can use this information, but quite honestly over the years I have seen a small percentage of batters that can make the necessary adjustments on the fly to take advantage of this information, lets face it, with the number of batters I see every summer that are pulling their front shoulder hips and hands directly to 3rd base on every swing how many are going to change their mechanics in the 1-2 seconds they have til the pitch arrives in the contact zone.
In the mens game "picking" pitches was developed to an art form, but, the batter never paid any attention to the people on the bench as they called out the pitches, it was simply meant to get to the pitcher, here is a great experiment, set your pitching machine up at the front edge of the circle, turn it up to 58-60 from that 35' distance(for 16-18 lower for younger), then see how many batters hit the ball out of the infield on the second pitch, obviously they know exactly where the ball is going and how fast, if knowing the location and speed of the pitch is such an advantage, why can't more of your girls hit the ball solidly on that pitch, that is what we are talking about isn't it?
Over the years I have had pitchers and catchers balk at setting up and throwing to spots when other teams are attempting to pick pitches and catcher location, my answer is simple, it DOESN'T matter, if we throw our game and hit our locations they cannot hit it anyway, and especially when they are confused and have their concentration being broken, FYI dad's your daughter can hear your voice a block away and when she hears it, she loses her focus immediately, so keep yelling from the stands while she is receiving a pitch.