The more simple a concept, the easier it is to behave in relationship to it. Just for a moment, set aside labels like “parental alienation” and a goal of “how to get your kids back” and instead focus on what really matters.
Note: The comments here are general and assume that one parent is on one end of the spectrum of not being self aware / trying to harm or destroy the other and the other is and well attuned the whole separated family system. In reality there can be a mix of both. This is why a competent mental health professional is important to discern where each parent is in the separated family structure. Also, this is snapshot. Things can shift over time.
Remember: It is not about getting your kids back. If you think it’s about that, then you are simply trying to move the manifestation of the pathology in such a way that the roles of the parents are reversed (one has, the other does not or one wins more time, meaning the other loses.)
It is about restoring a system that is out of balance and putting it back into balance whenever and in whatever ways possible. Even if that means small ways to let your children know there is a bond you acknowledge if they are doing and saying things that don’t readily communicate that. Even if they are grown, even if you have no opportunities at the moment to communicate at all.
Do whatever you can to bring yourself into balance and consider any action you take, any thought you think, any feeling you have in relationship to the question: Is this somehow moving the separated family system further towards being healthy or not? It is vital to know you moving you into balance is significant in addressing that question. I can tell you I am not alone in being amazed over and over again the things that seem to “happen” that have really changed things for the better by keeping focus on that question and addressing what I can.
As a reminder: Your ex is concerned about the outcome of winning and wants you to be as well. But when you are focused on tending to the whole separated family system, the process of your child feeling connected to both of you and what needs to be true of you to make the system as healthy as possible, you aren’t even in the same conversation. You are considering this in a way they cannot. You have an access to some peace of mind, even if fleeting, they are not capable of having. When you do it for yourself, you demonstrate to your child that they can too, no matter what.
Dr. Childress‘ illustration above* (I added in the goals comment and the extra arrow for emphasis) makes this as simple as I’ve seen it so far.
*This illustration depicts the mother as the one causing the cutoff family structure but this is just as true when it’s the father.