Am I misunderstanding the drill? I like this idea, but I am not sure many of my 7 & 8 year olds throw accurately enough to have a legit chance to knock over a water bottle at home plate when throwing from shortstop or second. I'm pretty sure it would take me 2 or 3 throws for a direct hit!!
For the less experienced players, you can hit the ball slower so they can charge it and be closer to home plate for an easier throw at the bottle. The more experienced players will get a harder hit ball making it tougher to field and creates a longer throw. Just experiment with the distances so each girl has an opportunity to get a point for their team.