Is the obligatory *Fitr* (Zakat al-Fitr) paid by one person on behalf of another permissible if done with permission?

Primary text

If a person whose *Fitr* is obligatory on another, such as a wife or a poor relative, pays their own *Fitr* having obtained permission from the one upon whom the obligation rests, the payment is valid without dispute. This is because the person paying acts as a representative (na'ib) for the one obligated.