Do full sisters inherit from their deceased brother, and what is their share, and the share of the mother and father from the inheritance, knowing that the mother is pregnant?

If a person dies leaving behind parents and a full sister, and their mother is pregnant by someone other than the deceased's father, and there are no other heirs, then the only inheritors are the father and the mother. The sister does not inherit due to the presence of the father, who bars siblings from inheritance, and the fetus also does not inherit because it is not the child of the deceased.

The Mother: Inherits one-sixth due to the presence of the sister and the fetus (assuming it is born alive), based on the verse: "But if he has brothers [or sisters], for his mother is one-sixth." If the fetus is stillborn, the mother inherits one-third, as there would be no brothers or sisters. The Father: Inherits the remainder by "ta'sib" (residuary inheritance) after the mother's share, based on the saying of the Prophet (PBUH): "Give the shares to those who are entitled to them, and what remains is for the closest male heir." The division of the inheritance must be postponed until the mother gives birth to ascertain the mother's share. The sister does not inherit in this case, but it is recommended to give her something from the inheritance when it is divided. It is advisable to refer such matters to Sharia (definition) courts to ensure that all rights, debts, and bequests are accounted for before dividing the inheritance.