A man and his wife, son and daughter died in an accident; how should their estates be divided?

If a number of
people die in an accident or in a collapsed building or fire, and they could
inherit from one another because of marriage or blood ties, the one who dies
later inherits from the one who dies earlier. If they die at the same time,
they do not inherit from one another. 

Shaykh Ibn ‘Abbaas
(may Allah have mercy on him) said: If two or more people who could inherit
from one another die in a collapsed building, by drowning, in a fire or
plague and the like, then there are five scenarios, one of which is that if
one of the two who could inherit from one another dies after the other, even
if only by a moment, then the one who dies later inherits (from the one who
dies first), according to scholarly consensus.

The second
scenario is that if they die at the same instant, there is no inheritance,
according to scholarly consensus.

End quote from
al-Fawaa’id al-Jaliyyah fi’l-Mabaahith al-Fardiyyah. 

Based on that, the
spouses do not inherit from one another in this case, because they died at
the same moment. 

Then we should
look at the case of each deceased person: who among his heirs was still
alive after his death? 

The heirs of the
wife are only her daughter, son and mother. Her siblings, whether through
both parents or through the father or mother only, do not get anything,
because they are prevented from inheriting by the presence of the son. 

Based on that, the
mother gets one-sixth and the rest goes to the son and daughter, with the
male getting a share equal to that of two females. 

The son and
daughter inherit from the husband, with the male getting a share equal to
that of two females. His siblings do not get anything because they are
prevented from inheriting by the presence of the son. 

The brother and
grandmother (mother’s mother) inherit from the daughter, so the grandmother
gets one-sixth, and the rest goes to the brother. 

The paternal
uncles (brothers of the father) and the grandmother (mother’s mother)
inherit from the son. The grandmother gets one-sixth and the rest goes to
the paternal uncles. The paternal aunts get nothing. 

The estate should
be divided in this order. Attention must be paid to giving the son and
daughter their shares from their father’s and mother’s estates, in addition
to whatever wealth of their own they had. And attention must be paid to the
fact that the grandmother (mother’s mother) will inherit from the mother
(the wife) and from the son and daughter. 

And Allah knows
best.