To whom does the authority of blood and blood money belong, and is it treated as an inheritance? What is the questioner's duty toward the children of his sister, who was intentionally killed?

The majority of scholars hold that the guardians of the blood in cases of retribution (Qisas) are all the heirs, men and women, young and old. If any one of them pardons, the right to Qisas is forfeited. Some, however, are of the opinion that the guardian of the blood is exclusively the 'Asaba (agnate relatives).

According to the view of the majority, the guardians of the blood for your sister are her son and her daughters.

If one parent kills the other, and they have a child, Qisas is waived and blood money (Diyah) becomes obligatory, because a child does not have the right to Qisas against their parent. The Diyah belongs to the heirs and is distributed among them according to the Islamic law of inheritance.