Is it permissible for a father to coerce his daughters into appointing their brother as their agent in the inheritance after his death, and will he incur wrath if they refuse to do so?

If a father's authorization for his brother to dispose of the inheritance after his death is intended to disinherit the daughters or restrict their control over their share, then it is not permissible in Sharia. This is because the inheritance transfers to the heirs immediately upon the death of the inheritor, and each heir owns their Sharia-prescribed share. A father has no guardianship over the wealth of his adult, mature children during his lifetime, nor does he have the right to appoint a guardian over them after his death. This is a form of deception aimed at disinheriting daughters or diminishing their Sharia-prescribed share, which is characteristic of the practices of the pre-Islamic era of ignorance (Jahiliyyah), oppression, and aggression.