Is what a father pays to marry off his son considered an obligatory expenditure, a gift, or a grant, and is it permissible for him to favor some of his children in giving gifts after marrying off his son and paying his marriage expenses?

The fatwa adopted by us dictates the obligation of equality between children, male and female, in gifts and endowments, unless there is a necessity that warrants preferential treatment. What a father spends on marrying off his children in a reasonable manner falls under the category of expenditures, not gifts. However, a father's gifting of apartments to his sons without including his daughters constitutes preferential treatment in a gift, not an expenditure, because housing is not exclusively tied to owning a house. Therefore, compensating the daughters with money equivalent to the apartments is the correct approach.