the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
We understand from your question that your father died leaving no other inheritors besides two wives, two sons, and six daughters. On the basis of this assumption, the answer will be as follows:
The two wives share in 1/8th of the estate. This should be divided equally between them, so that each wife received 1/16th of the entire estate.
The remainder of the estate – 7/8ths – will be divided among the children, with each son receiving a share twice as large as the share of each daughter.
The best way to facilitate this is to take the total value of the deceased’s estate and divide it into 80 equal shares.
Each wife will receive 5 shares. (5/80=1/16)
Each son will receive 14 shares.
Each daughter will receive 7 shares.
Source: Islam Today