Half of the house belongs to the parents. In the event of the death of both parents at the same time, the heirs will inherit in the first place, ie your husband and his sister equally, each will receive one quarter of the house. So your husband will own ¾ the house and his sister ¼. In the event of the death of one of the parents, his or her spouse and both children will inherit equally. In this case, only the house that belonged to the deceased will go to the inheritance. It will be divided equally among the 3 heirs in the first row. In the event that your husband dies first, you and your children will inherit half of the house, also in equal shares.