Is it permissible to secretly give saved money to a needy sister, fearing the parents' anger if they inquire about the money's whereabouts?

A person's eagerness for good increases. If it is possible to allude to giving charity to the parents without angering them, then let him donate the money. By doing so, he combines the benefit of charity with not angering his parents. If this is not possible, and he is certain of their anger, then let him speak to them with gentleness and kindness, and explain to them that he is not in need of this money, and that charity is better for him and brings a greater reward. If they are convinced and pleased, then that is well and good. Otherwise, he can donate some of the money and keep some, such that the amount of charity does not exceed what would anger them.