What is the ruling on implementing a father's will that includes allocating 500 Euros monthly to his unmarried sisters, dedicating the rent of two apartments to my mother for her lifetime in addition to her rightful inheritance, and distributing the inheritance according to Austrian law, and does this will contradict the provisions of Islamic Sharia, especially after the heirs have agreed to implement it fully according to Sharia?

First: The father's bequest of a sum from the apartment's rent to his three sisters is a valid and enforceable bequest within the limits of one-third, as it is a bequest of a usufruct to a non-heir.

Second: If the bequest is for 500 Euros from the rent of all apartments, and this amount is less than one-third of the estate, then it must be executed. If it is from a specific apartment, then the value of that apartment is considered when determining the one-third.

Third: His bequest that the rent of the two apartments go to the mother, who is an heir, is not valid unless the other heirs agree. Anyone who does not agree has the right to their full share of the two apartments and their rent.

Fourth: His bequest to distribute the inheritance according to Austrian law cannot be executed if it contradicts the Islamic division of inheritance, because the ruling of Allah Almighty is more deserving of execution.