Honestly, as the legal guardians of the girls that did the stabbings, their parents ARE responsible under the law. The fact that we rarely push to punish the parents doesn't make it unreasonable to think that they might bear some of the blame. We're fast enough to blame parents if a kid finds a gun and shoots a cousin. How is this different? When will we realize that kids need watching, and it starts AT HOME?
It's well past time that we started to expect people to be responsible. You bring a child into this world, and you are responsible for raising that child, feeding them, educating them, and teaching them how to be a productive member of society. You don't buy them a laptop at ten and say, "Have fun." You make sure they know what's right and what's wrong. It's no one else's responsibility.
Yes, the other girl is alive, but can you imagine how this will color her life? Not only now, when she's injured, in the hospital, and no doubt scared half to death, but years from now. Who's going to be there when she suffers PTSD, or has nightmares? Who puts her life back together for her and makes it all okay again? No one can give her back what she lost thanks to these two little monsters.