There are others that conribute, directly and or indirectly to parental alienation hence child abuse by way of supporting the alienator in different ways
Extended family, friends
Close family members such as grandparents, uncles, aunts, cousins etc and even friends by supporting the alienator when it becomes clear to them just what is going on are in fact supporting alienation.
Even if a family member becomes suspicious of the alienator it is in fact in the children’s best interests for them to question what is happening, if they do not then they themselves by default are contributing to the abuse.
Supporting another person at a time when they need support is commendable, but supporting them to the point that morals and truth become a casualty is just plain bad support in anyone’s view.
We all have a duty to stand up for the truth and for the children in their best interests, if we don’t do just that then we are supporting parental alienation and saying that we don’t care that the children are being abused.