And the runner on 3rd can do anything that she wants to do, until the batter/runner touches 1st base.
Amy I have to disagree with you here, but I am open to a better explaination from Bretman or other ump. We always taught our girls that with a runner on 3rd and batter gets walked for catcher to throw back to pitcher immediately and for pitcher to keep ball in glove and stare at runner on 3rd. If Pitcher has ball in circle, and is not making a play on any runner then all runners have to commit to going back to base or to next base. Otherwise they are out. Whether or not batter/runner crosses first has no bearing on it. It is also my understanding that what is considered making a play is pretty wide open to umps discretion. Even looking at a base runner with ball in your throwing hand can be considered making a play, even if it is kept at your side.
BTW we had this exact scenerio a couple years ago in middlle school ball (high school rules). Our pitcher looked back runner at 3rd and runner did not move back to bag. Runner was called out and opposing coach went nuts. Claiming batter/runner had not touched 1st so play was not over. Ump said did not matter. BRETMAN Help!