Is it permissible to pay Zakat al-Fitr on behalf of deceased parents, brothers, and sisters? And is Zakat al-Fitr obligatory for the wife?

Zakat al-Fitr is obligatory for the living. It is recommended to give it on behalf of a fetus. As for the deceased, there is no text regarding this, but one can give charity on their behalf. You must pay Zakat al-Fitr for your wife and those you support, such as your children and others, based on the hadith: "Pay the sadaqa of Fitr on behalf of those whom you support."