Question: If a man has several children—some of them grown and self-sufficient through their earnings, and some of them young and not earning—does the father have the right to give to the younger ones and not to the older ones? Or must he maintain equality between the older and the younger?
Answer: If the younger children are in need and the older ones are not in need, then it is permissible for the father to give to the younger ones, to meet their needs and remedy their poverty, in what is customary of maintenance and what attaches to it. Beyond that, he must maintain equality among all the children.
What appears to me concerning equality is that, when he gives to his children, he gives each what befits him. Thus, if he gives his son clothing, a jambiyyah (dagger), and a rifle, he gives the daughter what befits her of clothing and jewelry.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2