ANSWER: 

They are sinful and will be held accountable by Allah for this unless they repent however, your father is not allowed to break his ties with them because of this. Allah mandates that he uphold ties of kinship with them while anticipating the reward from Allah alone.  

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My father’s parents didn’t divide the property according to sharia . After his father’s death the brothers n sisters took hold of all property n didn’t give him a single penny . Now should my father meet them and keep relation ship with them , although they hurt us by depriving us of our share in property . Pls explain in detail.

Fiqh of the family, Inheritance | January 11, 2018 1:16 am
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According to the law of the land anything bought after marriage is automatically shared ownership regardless who bought it and the name under it. My father bought a house, now that he passed away do the inheritance must be halved first then divided as my mother is still alive eventhough name of ownership is only my father.
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Sheikh, i wanted to enquire that is it allowed to write will for a women ( Leaving 1/3rd for charity ) of her property for her children specifying what belongs to whom? That is, if she has built 2 houses, can she write specific Will that 1 goes to her son and other to her daughter? And a specific small area thats could be used as a store area for 1 of her child?