Does one of the sons have the lawful right to inherit part of the family home on the ground floor, given that the first floor was built by the brother with his own money following a gift from the father, and the second floor was built by the sister with her own money following a gift from the father?

If the father grants the air space of his house to his two sons to build upon, then the two floors and the air space become their property and are not included in the inheritance. However, if he merely permits them to build, this is a loan ( 'ariyya ) that ends with the father's death, and the first and second floors become the property of all heirs, with the two brothers being compensated for the value of the construction.

The family home (ground floor) is a common inheritance for all heirs, with the male receiving the share of two females. Designating male children for a gift while excluding females is impermissible, and justice between children is obligatory. What is preferred by us is equal distribution among all (males and females).

If the father shows preference among his children in a gift and dies before reclaiming it, then the gift becomes established for the recipient and binding, and the remaining heirs have no right to revoke it. This is the opinion of most scholars.

The matter of inheritances is serious and complex, and they should not be divided without consulting the Sharia courts.