Is it permissible for a husband to give his Zakat to his wife's children who live with him and whom he supports financially?

Zakat is not permissible for children if their mother is capable and obligated to spend on them. However, it is permissible for the husband to give his zakat to his wife's poor children if their mother is unable to spend on them, even if the husband spends on them voluntarily, because the husband is not obligated to spend on them.