Is it permissible to give a woman's zakat on gold to her poor mother or sister and their children without informing them that it is the zakat on gold?

It is not permissible for a woman to give her Zakat al-mal (obligatory charity on wealth) to her mother because her mother is among those whose maintenance is obligatory upon her. However, it is permissible to give it to her sister and her children; in fact, they are more deserving of it, as they are relatives.