Is Zakat al-Fitr obligatory for one who sponsors an orphan?

Zakat al-Fitr is obligatory upon an orphan from their own wealth if they possess inherited wealth or wealth given to them as charity. If they do not possess wealth, then those who provide for them are not obligated to pay Zakat on their behalf, as long as their provision is voluntary and not obligatory. This is because Zakat al-Fitr is only obligatory for those whose maintenance is a duty, not for those who voluntarily provide for others. The hadith: "Pay the Fitr for those you maintain" is weak.