Kids who are alienated usually don't live with their parents. This explanation does not differentiate between abused kids who live with their abuser or don't. Clearly it is comparing behaviors in the context of abuse versus alienation accusations.
In any event, abused kids are afraid (not openly defiant) of their abusers far into adulthood and long after they are removed from their presence. It appears you may not have experience with either abuse or the abused. You're lucky.
This may be true in most cases, but I have a child with me who is openly defiant because of abuse, complex including physical, emotional, alienation, years of being unheard by 'authorities'. He is receiving help for this, but he is either a wonderfully polite, well mannered, extremely compliant (overly so), or when faced by social workers, his abusers and occasionally myself when I enforce boundaries, he becomes exactly as these children are described, he refuses to drink to the point he becomes constipated.
I don't know whether it is a result of fear of dad, alienation by mum or a fear/dread/lack of trust of the court system (not helped by recent events), whatever the cause someone needs to hear these children, alone and without fear of their information becoming part of a court case or newspaper article. They have NO-ONE to trust, no safe place to turn to vent. ALL of the adults involved need to take a long hard look at themselves here or they are doomed to repeat this dysfunctional cycle as they become adults themselves.
The court should probably start with some thera play, without parental involvement, start weaning mum away from her unhealthy attachment (obsessively possessive IMO) to the children, allow dad to just be in the same room if need be, the kids will tire of not talking. Have a therapist talk to dad and provide him with some open ended small talk for use with the children. Start allowing the siblings to become individuals by promoting separate activities, they are unhealthily 'one unit'.
Oh dear, have monopolized this discussion enough for one night. Gitana, I love your insight, you are one smart cookie. I admire your passion, we have simply been on different sides of the law, I have experienced abuse and fled a country. The courts ruled in my childs favor, but the reality is very different from the 'legal claims and rules'. I then became the voice for 2 littles who were abused and failed repeatedly by the 'system'. They are also now safe here with me. The Family Court worked for me in both cases, in both countries, but I am also aware (as an advocate) that it is often a case of the best read lawyer and not best interest of the child.