From what I have read and researched (a lot) you point out ALL the features that you, your psychologist, I and the specialist lawyer know are concrete signs of NPD and you hope and pray the judge will see the narcissist for what they are. But you do not mention NPD.
Eg " he/she always drives really fast in the car when angry with me/my DC to frighten them/me. He/she forged my signature in the bank and pretended he/she hadnt. He/she told everyone I was an alcoholic/neglectful parent/drug addict and isolated me. He/she would only give me access to money for food and checked my receipts etc etc. Whatever it may be. Covert narcissists are different from grandiose (as you will know) Covert narcissists=extremely insecure master manipulators and liars. Whole life walking on eggshells.
You do not "armchair diagnose" them, (as you have already seen the attitude you will get on this thread.) Your lawyer will know this. I have not once mentioned narcissim (in the many ridiculous delaying proceses/interviews I have been through so far with SS, court psychologists, (my poor teenage DC)) and will not. Just answer facts and stay cool.
Believe me it is hard. They will not negotiate one jot. They are out to destroy you. But... being someone with NPD means they will trip themselves up.
They have a skewed reality. The truth will out and you need to look very calm and sane.
Any emails/evidence is always useful too.
Do try and find the experienced lawyer though. (Mine isnt: legal aid, but I have prepared everything so carefully it will be fine, I hope!)