Is it permissible to complete the finishing of the house and reside in it if some of the siblings object despite their previous approval, and was the gift properly executed in a way that grants the right to build? If not, is the questioner to be blamed if he files a lawsuit for partition (removal of co-ownership) after four years to sell the house and distribute the inheritance?

The questioner's eagerness to maintain kinship ties with his brothers is a virtuous trait. The brothers' agreement to build on the roof before the father's death constitutes a relinquishment of a right before it became due. The parents' house is an inheritance, and the two elder brothers have no right to delay its division. Building on the roof is considered a temporary loan (عارية), and the builder is entitled to the value of his demolished construction upon the termination of the loan. The house should be appraised without the building, then the building should be appraised as demolished. If custom considers the father's gift of the roof to his son a valid gift, then it should be acted upon. The building permit being in the father's name does not negate the questioner's right. Going to court may be necessary to distinguish between overlapping rights, while maintaining compassion among the brothers.