Is the ruling that children are not entitled to a gift fair, especially given the father's final and irrevocable waiver to them?

We cannot rule on the judge's verdict or review the case due to our lack of knowledge of the verdict's details. However, a judge's ruling does not make lawful what is unlawful, nor does it make unlawful what is lawful, for the Messenger of Allah, peace and blessings be upon him, said: "Indeed, you bring your disputes to me, and perhaps some of you are more eloquent in presenting their arguments than others. So, whoever I rule in his favor concerning something that rightfully belongs to his brother, based on his words, then I am only cutting off a piece of hellfire for him; let him not take it." Therefore, whoever deceives the judiciary and takes the right of another, let him know that the judge's ruling does not permit him that, and he will be held accountable for it on the Day of Resurrection.