Is it permissible for a man to give his foster daughter from Zakat if she is poor?

A man is not permitted to give his zakat to his poor children, because he is obligated to provide for them. An exception to this is foster children (from رضاعة, i.e., suckling), to whom it is permissible to give zakat, because he is not obligated to provide for them. Fosterage (رضاع) only establishes prohibitory kinship for marriage, not for other rulings of lineage such as maintenance and inheritance.