To clarify the Siblings' relationship, observe the following family chart that depicts my actual family situation. These are unique situations that may take place one in thousands. Islamic Inheritance law did not disregard this relationship even though few of these situations may exist. However, the chances of existence in such relationships may increase over time due to the increased death rate and divorce due to our economic challenges. There are three types of siblings; Full (or real) siblings related to both mother and father. Paternal (or half, consanguine) siblings related to the father (do not share lineage). Maternal (or uterine) siblings related to the mother (share the same lineage). Full siblings have the same father and mother (share the same lineage). Maternal and Full Siblings have the same mother but different fathers. Maternal and Paternal Siblings have the same father and different mothers. Full siblings include Full brothers and Full Sisters. Paternal siblings include Paternal brothers and Paternal sisters. Maternal Siblings include Maternal Brothers and Maternal Sisters. Maternal siblings inherit fixed shares 1/6 (or one-sixth) if single and 1/3 (or one-third) if multiple. Full and Paternal brothers inherit shares similar to sons (i.e., independent residuary or joint residuary with daughters). Full and Paternal sisters inherit shares similar to daughters (i.e., 1/2 or one-half, 2/3 or two-thirds, 1/6 or one-sixth, or joint residuary with sons). The sibling's share can vary in certain conditions due to the decrease or increase of total shares under the Radd and Awal (or Aul) scenario. In the absence of brothers, the sister's share can vary in certain conditions due to the decrease or increase of total shares under the Radd and Awal (or Aul) scenario.
Allah, the Most Glorified and the Most High, knows the best. As a human, We are limited to everything and can not perceive it in totality...