NSW Parental Alienation as Defamation?

Is it at all possible for a parent targeted in an acrimonious, ongoing parental alienation agenda to bring action against the other parent on grounds of defamation? One parent has been disparaged and falsely represented by the other parent to their two children as well as to several other individuals associated with the children (school principals, teachers, family therapists, etc). Family Court orders have been in place since April 2011, but the alienating parent has defied the orders; 3 contravention applications are currently before the court. It should be noted that the targeted parent has twice returned to court to fight frivolous and vexacious allegations, on both occasions the court finding in favour of the targeted parent (on the last occasion, the Local Court judge strongly chastised the targeting parent's obvious agenda and misuse of the court's time and resources.)