Is the father sinful for having his daughters sign to receive less than their legal share of the inheritance, and how should the inheritance be divided now?

If a father owes his daughters a debt and dies before repaying it, the debt does not lapse with his death. It must be settled from the estate before its distribution, as Allah the Almighty says: "after any bequest has been fulfilled or debt paid." Moreover, attempting to deprive daughters of their inheritance and wronging them in the division of the estate is an act for which the doer is sinful. Allah has threatened those who commit such acts with a severe punishment. He, the Almighty, says: "These are the limits set by Allah. And whoever obeys Allah and His Messenger will be admitted by Him to Gardens beneath which rivers flow, abiding eternally therein; and that is the great success. But whoever disobeys Allah and His Messenger and transgresses His limits – He will admit him to Fire, abiding eternally therein, and he will have a humiliating punishment." It is obligatory to enable daughters to receive their full share of the inheritance, and to divide the estate according to the legal shares.