Sounds like the adults in the situation are all on the right track. For your DD, I'd recommend martial arts*. A nurturing dojo (not a violent fight club or an impersonal chain) can be a wonderful place for learning about confidence, personal space, setting boundaries, dealing with conflict, etc. Your DD will gain valuable tools that can serve her well through the rest of her life.
I swear this is probably the fourth or fifth time I've recommended martial arts here... sorry for being a broken record. In fact, I'd recommend it for the other little girl as well (though not at the same place obviously!). It's a great way to learn self control, channel angry feelings, and sooth anxiety in a safe setting.
