Can he give zakaat al-fitr to his half-siblings?
Question

                I have half-siblings from another mother, and our father is deceased, and they need money. Is it permissible to give them zakaat al-fitr?.
Praise be to Allah.Zakaat al-fitr is to be 
    given to the poor and needy, because of the hadeeth of Ibn ‘Abbaas (may 
    Allaah be pleased with him): The Messenger of Allaah  (peace and 
    blessings of Allaah be upon him) enjoined zakaat al-fitr as a purification 
    for the fasting person from idle and obscene speech, and to feed the poor. 
    Narrated by Abu Dawood (1609) and Ibn Majaah (1827); classed as hasan by 
    al-Albaani in Saheeh al-Targheeb (1085). 
Ibn al-Qayyim (may Allaah 
    have mercy on him) said: 
It was his way to single 
    out the poor to receive this charity. End quote. 
Zaad al-Ma’aad 
    (2/21). 
Having established that, 
    then we know that a poor relative is more entitled to zakaah than anyone 
    else. 
But it is not permissible 
    for anyone to give his zakaah to those on whom he is obliged to spend. 
You have to spend on them 
    if you would inherit from them. If you would inherit from them then it is 
    not permissible to give them zakaah, but if you would not inherit from them 
    then there is nothing wrong with giving them zakaah. 
If you would inherit from 
    some of them and not others, then give zakaah to those from whom you would 
    inherit. 
You are not obliged to 
    spend on them unless you have wealth that is surplus to your needs and those 
    of your family. If that is not the case then you are not obliged to spend on 
    them, because you are not able to do so. In that case you may give them your 
    zakaah, even if you would inherit from them. 
See also the answer to question no. 106540. 
And Allaah knows best.