Parental Alienation Syndrome- what can the kids do?

I am not divorced but my neighbors went through perhaps the most conflicted, lengthy divorce I have ever witnessed. 3 year to divorce and though it is final - the war is far from over.  They have 2 beautiful children who have been severely psycholigically harmed dring this process. Both parents have so much anger, one appears to manipulate the children against the other and communicates constantly about how terrible the other is. I think it's leading up to a 2nd custody battle. I've known the children since their births ( they're 11 and 17 now) and I have a strong bond with both of them. I've been trying to be a "neutral territory for them to talk and feel whatever they need. The older has become very protective of the younger. They need the bitterness to stop. It is confusing to them - they don't kow who they should love - which is the saddest thing in the world. The one thing they are sure of is they have to choose. Thing is - that's so wrong. I'm considering arming them with a little info about  PAS and helping them tell both their parents they can't listen to it anymore. I need your thoughts. Please help. These kids have changed so much from the confident, fun lovign kids they were 3 years ago. Thanks so much.