@WhatHappenedToThose
For you to claim that there is no such thing as parental alienation is quite ridiculous.
The British courts certainly accept the existence of alienation as does CAFCASS.
Here is the CAFCASS definition of parental alienation:-
"When a child's resistance/hostility towards one parent is not justified and is the result of psychological manipulation by the other parent."
To that may be added that the manipulation of the child by the other parent need not be malicious or even deliberate. It is the process that matters, not the motive.
Signs of alienation may include portraying the other parent in an unduly negative light to the child, suggesting that the other parent does not love the child, providing unnecessary reassurance to the child about time with the other parent, contacting the child excessively when with the other parent, and making unfounded allegations or insinuations, particularly of sexual abuse.
There are no end of court cases where parental alienation has been central to the outcome.
For example, a recent case in the court of appeal where the daughter was taken from the mother and placed with the father:-
Re S (Parental Alienation: Cult) (2020) EWCA Civ 568
Or another case in the High Court:-
RH (Parental Alienation) (2019) EWHC 2723 (Fam)
where the son's residence was transferred from the mother to the father. A quote from the judgment:-
""Mother's opinions about the father have been transferring to H gradually over time, and are now complete, with his independent rejection of contact. Mother herself would say that this is the result of H seeing 'who his father really is', but H's presentation suggests it is more likely to reflect alienation. Mother's views of the father are entrenched, and the prognosis for any shift in that view, if H remains with his mother, does not look promising."
"Unfortunately, therapeutic intervention aimed at a restoring H's relationship with his father whilst in the care of his mother is ill-advised, not only in light of the research evidence, but the failure of any previous threat of change of residence to change the course of this case or mum's stance, with the consequence that H now has no relationship with his father.
Even though there may be transient distress, particularly as H is now settled in his secondary school, with friends, this needs to be weighed against the need for removal from his mum, to protect him from further harm, in the form of the consequences of complete loss of his dad."
"H is currently prioritizing his mother's needs over his own and no longer sees his relationship with his father as bringing anything but pain and complication into his life. Development of such rigid schemas may, among other difficulties preclude him from making good enough sense of his social and emotional world to be able to negotiate his relationships successfully as he matures."
I could give you page after page of other similar court judgments.
Parental alienation is a very real thing and the courts do transfer residence (in, admittedly, extreme cases) where this happens.