What is the ruling regarding someone who registered all of his properties in the name of his unmarried daughter, under the pretext that she took care of him, while the rest of his children financially supported him, and by doing so, he deprived all other heirs after his death? And do the brothers have to financially support this sister after she has taken all of the inheritance?

The inheritance of the deceased, who left behind five sons and three daughters and no other heirs, is to be divided among them by way of ta'ṣīb (residuary inheritance), with the male receiving the share of two females. This means the inheritance is divided into thirteen shares: each son receives two shares, and each daughter receives one share.

As for registering properties in the daughter's name: if it is a will made after death to an heir, it is legally forbidden unless the rest of the heirs consent. If it is a gift made during his lifetime, then the condition of the giver (whether he was in a life-threatening illness or not) and whether the daughter took possession of the properties or not must be considered, as each situation has its own ruling.

As for the brothers' maintenance of their sister: if the sister is wealthy, she is not entitled to maintenance. If she is poor, the preponderant opinion among us is that maintenance is obligatory for the brother if he is an heir to his sister, has surplus beyond his own and his dependents' needs, and the sister is poor. Kindness to the sister is also obligatory.