Protecting the property of the minors and only disposing of it in a way that achieves their benefit
It is impermissible to take any amount of minors' money, whether owned through inheritance, charity or anything else, to finance any affair of any of them. Rather, it is obligatory to keep their money and even invest it to their advantage. Actually, their money should be used to provide for them according to what is customarily reasonable and then handed over to them when they reach maturity. Accordingly, you should finance your brother's marriage from his own share and from the charity donated specifically to him.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.