Do all the heirs share in the compensation amount for the demolition, or is the amount specific only to what was calculated for two floors, given that the brother built two additional floors after the father's death and without the permission of the heirs?

If one of the heirs builds on jointly owned property with the permission or knowledge of the others, and without their objection, then the structure belongs to him, and he receives its value separately upon sale or demolition. So, if the house is demolished and the heirs are given compensation, the compensation is divided so that the builder receives the value of his construction. Shuraih stated, "Whoever builds on the land of a people with their permission, he is entitled to the value of his construction." Ibn Taymiyyah said that the land is the right of the heirs, but as for the building, if the builder constructed it with his own money, he has the right to take it, and he is responsible for guaranteeing the old building that belonged to the heirs. If the land and building are taken with compensation, the value of the building is estimated by experts and given to the builder. There is no objection if the adult heirs agree on something else.