Let me suggest, especially if your daughters are just starting out, that you purchase them a "Game Face". Make them practice with it and always wear it in games. One of the pitchers on my daughter's travel ball team was hit with a line drive square between the eyes during our local league softball and was sent to Vandy with multiple skull fractures. I can only imagine how bad it could have been if it had been hit by a travel ball player. It's not worth the risk when there is equipment available to help avoid alot of these injuries.
As far as how your daughters finish their pitch, I had a pitching instructor tell me once that it doesn't necessarily matter how much they do or don't close ...what really matters is if they have their balance enough to defend themselves from a ball that's coming right back down their throat. Wise words from a wise man.