Is it considered unjust and unfair among children for a father to favor his son by educating him in private schools, while depriving his daughters of the same opportunity despite being able to enroll them, and to dedicate such an advantage solely to the son for the sake of his better future?

It is obligatory to be just between children in gift-giving, not in the expenses given to each according to their needs. For expenses are to fulfill a need, and justice in them is that each is given what they need. So, if a son needs a special school that qualifies him for a prestigious job, and the daughters do not need such jobs, then there is no harm in preferring the son in that, while taking into account the selection of government schools for girls that provide a suitable environment, cleanliness, and quality education. Otherwise, they should be enrolled in private schools that suit their circumstances.