Originally Posted by ElizabethN
Another thing that was mentioned is that you should really try not to let two girls get into a best-friends relationship where they have no other friends, as it gives them too much power over one another.

I agree 100%. You don't have to cut off all out-of-school contact (like I did with my DD & her Girl X), but if you "water down" the influence and power of your DD's Girl X with other friendships, it will really help.