How to Be Just in Expenditure and Giving Gifts

Question :

I have a daughter who is employed, she gives her mother a portion of her salary, and I am not in need of her salary. But she gives me more than she gives her mother. My second wife has a son who works with my money and he profits and gives his mother something from his income. The third wife has small sons and she has no income from any source and when she asks me for money, I give it to her and I give her co-wives the same as I give to her, out of fear of doing injustice. What I fear is, if I give her more than her co-wives, due to the fact that they have children who give them something and I am interpreting the Hadith:
"You and your property belong to your father."

- is what they receive from their children of mine, and do I have to give the third wife the same, or not? I request your advice..

Answer:

If the situation is as you have described it, that the sum given by your daughter to her mother is from her salary, and the sum given by your son to his mother is from his share of the aforementioned profit. Then you are not obliged to give your third wife the same amount as is given to her co-wives by their children, because the giving of a daughter to her mother, and the giving of a son to his mother, is considered to be an act of kindness from each of them towards the mother. So you are not obliged to give the third wife an equivalent amount; you are only obliged to give each of your wives what is sufficient for her and for her children, according to what is reasonable.

Source:
The Permanent Committee
Fatawa Islamiyah, Vol. 5 Pages 364-365