The estate of the deceased who left behind a wife, sons, sisters and grandchildren

Dear Brothers & Sisters,
As-Salaamu-Alaikum wa Rahmatullahi wa Barakatuh. (May Allah's Peace, Mercy and Blessings be upon all of you)
One of our brothers/sisters has asked this question:
My father passed away recently (may Allah (swt) forgive his sins and bless him) leaving behind family as follows:  Wife , 4 sons (3 married, 3 grandchildren) ,  3 sisters (one married, one widow, one spinster) ,  Mother and Father .  I have read the Qur'an, but found the conditions of inheritance a little complicated to understand.  Please inform me of the correct split of the estate of my father, and also how much, if any, of that estate can go towards charity.
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Answer:

Praise be to Allaah.

What you have to do is refer to the nearest sharee’ah court to divide the inheritance, after paying any debts that are owed and executing the will of the deceased with regard to one-third or less of the estate. Then the division of the estate among the heirs should be done after the necessary conditions have been met and there is nothing to prevent it being done. In any case, once the necessary conditions have been met and there is nothing to prevent the estate being divided, and there are no other heirs apart from these: 

-The wife should take one-eighth (1/8), because there are offspring who are entitled to inherit.

-The father should take one-sixth (1/6), because there are male offspring who are entitled to inherit.

-The mother should take one sixth (1/6) because there are offspring who are entitled to inherit

-The remaining children should take equal shares, so long as they are all male. But the grandchildren and sisters doe not receive any share, because there are offspring who are entitled to inherit, and these are the sons. 

Whatever written of Truth and benefit is only due to Allah's Assistance and Guidance, and whatever of error is of me. Allah Alone Knows Best and He is the Only Source of Strength.
Your brother and well wisher in Islam

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