If he dies and leaves behind a father, mother, Christian wife, and brothers and sisters both full- and half-siblings, who among them inherits from him?
Question

                I am in the process of writting my last will and Ifound it challenging due to a little complicated situation, I am explaining here within:
I am married to a Christian woman (she is not muslim but she is a believer) our marriage was celebrated in the mosque. I have three full sisters all married, two half-sisters from my father side and 3 half-brother from my father side and my parents: father and mother.
My parents are divorced since 10 yeras ago, my father doesnt support my Mom who lives alone in a home I bought for her, I take care of her living and expense when she needs. I have no regular contact or news from my half-brothers and half-sisters. I kept contact with my father who remarried several times since. I would like to know what is the prescribed portions of IRTH (inheritance) that apply for my heirs should they inherit me after my departure.
Praise be to Allah.
      Firstly: 

    Your saying that your Christian wife is not a Muslim but she 
    is a believer is a contradiction in terms and is not correct, because the 
    one who is a believer is a Muslim. Perhaps you mean that she believes in the 
    existence of God or that she believes in her religion. This and similar 
    matters cannot be described as faith or Islam unless she believes in the 
    Messenger of Allah Muhammad (blessings and peace of Allah be upon him) and 
    she believes in all the Messengers of Allah. 

    The Christians are disbelievers and cannot be described as 
    Muslims, let alone believers. Allah, may He be exalted, says (interpretation 
    of the meaning):

    “Surely, disbelievers are those who said: ‘Allah is the 
    third of the three (in a Trinity)’”

    [al-Maa’idah 5:73] 

    “And (remember) when Allah will say (on the Day of 
    Resurrection): ‘O ‘Eesa (Jesus), son of Maryam (Mary)! Did you say unto men: 
    Worship me and my mother as two gods besides Allah?’ He will say: ‘Glory be 
    to You! It was not for me to say what I had no right (to say)’”

    [al-Maa’idah 5:116]. 

    In Saheeh Muslim (153) it is narrated from Abu 
    Hurayrah (may Allah be pleased with him) from the Messenger of Allah 
    (blessings and peace of Allah be upon him) that he said: “By the One in 
    Whose hand is the soul of Muhammad, no one among this nation, Jew or 
    Christian, hears of me then dies not believing in that with which I was 
    sent, but he will be one of the people of the Fire.” 

    Shaykh al-Islam (Ibn Taymiyah – may Allah have mercy on him) 
    said: 

    The Jews and Christians are disbelievers in a sense that is 
    clear, and that is well established and well known in the religion of Islam.

    End quote from Majmoo‘ al-Fataawa, 35/201 

    Secondly: 

    Inheritance refers to the living taking charge of the wealth 
    of the deceased because of ties of blood or marriage. 

    The inheritance is not determined until after the death of 
    the one from whom the wealth is inherited, after which we may see who among 
    his heirs is entitled to take over his wealth that he left behind, according 
    to the shares allocated by Allah. 

    We cannot at present specify who will inherit from you after 
    you die, because we do not know who will die first; perhaps you will inherit 
    from them or perhaps others will inherit from you. 

    But if we assume that you have left all of these people 
    behind, then your inheritance goes to your father and your mother; and your 
    wife and brothers and sisters, whether they are full- or half-siblings, do 
    not get anything. 

    With regard to your wife, she does not inherit from you 
    because she is a non-Muslim; a non-Muslim cannot inherit from a Muslim and a 
    Muslim cannot inherit from a non-Muslim. 

    See the answer to question no.
    26171 

    With regard to your brothers and sisters, none of them 
    inherits because the father is present. 

    Allah, may He be exalted, says (interpretation of the 
    meaning):

    “if no children, and the parents are the (only) heirs, the 
    mother has a third; if the deceased left brothers or (sisters), the mother 
    has a sixth. (The distribution in all cases is) after the payment of 
    legacies he may have bequeathed or debts”

    [an-Nisa’ 4:11]. 

    Ibn Katheer (may Allah have mercy on him) said: 

    The third scenario with regard to parents is if parents are 
    present along with siblings, whether they are from both parents or from the 
    father or from the mother. They do not inherit anything if the father is 
    present, but despite that they change the share of the mother from one third 
    to one sixth. So if there are siblings, her share is changed to one sixth. 
    If there is no heir apart from her and the father, the father gets the 
    remainder (of the estate).

    End quote from Tafseer Ibn Katheer, 2/199 

    Abu’l-Qaasim al-Khuraqi (may Allah have mercy on him) said: 
    The brother and sister, whether they are full siblings or through the father 
    only, do not inherit if there is a son or if there is a son’s son 
    (grandson), no matter how far the line of descent extends, or if there is a 
    father. 

    Ibn Qudaamah (may Allah have mercy on him) said: The scholars 
    are unanimously agreed on this, praise be to Allah. That was mentioned by 
    Ibn al-Mundhir and others.

    End quote from al-Mughni, 6/163 

    Based on that, the mother inherits one sixth and all the rest 
    goes to the father; none of the siblings or the wife inherits anything. 

    The siblings in this case block others and are blocked. They 
    block the mother in the sense that they reduce her share from one third to 
    one sixth, and they are blocked by the presence of the father, because he is 
    closer to the deceased than them. The Prophet (blessings and peace of Allah 
    be upon him) said: “Give the shares of inheritance to those who are entitled 
    to them, and whatever is left goes to the closest male relative.”

    Narrated by al-Bukhaari, 6732; Muslim, 1615 

    But you should understand that you have the right to bequeath 
    part of your wealth to those who will not inherit from you, up to a limit of 
    one third of what you leave behind. So if your wife will not inherit from 
    you because she is Christian, and your siblings will not inherit from you, 
    because they are blocked, then if you wish you may bequeath some of your 
    wealth to whomever you want of these people, either to all of them or some 
    of them, so long as what you bequeath is not more than one third of the 
    entire estate that you leave behind. And if you do not make a bequest, there 
    is no sin on you; if you make a bequest to some of them and not others, 
    there is no sin on you either. 

    You have to honour your father and mother and treat them 
    kindly, and uphold ties with all of your siblings, males and females, full 
    siblings and otherwise, because that is what Allah has enjoined upon you. 

    And Allah knows best.