What is the inheritance share of a stepmother who has not given birth, and is it permissible for the husband's son to take her share of the inheritance with her consent?

The wife's share is one-eighth due to the presence of a lineal descendant, whether from her or from another wife, based on Allah’s Almighty saying: "But if you have a child, then for them [the wives] is one eighth of what you leave." The remainder goes to the son by way of ta'sib (residuary heirship). Thus, the inheritance is divided into eight shares: one share for the wife and seven shares for the son. The son is not entitled to take his stepmother’s share unless she willingly relinquishes it, provided she is an adult of sound judgment. Inheritance matters are extremely serious and complex, and it is not sufficient to rely solely on a fatwa; rather, they must be referred to the Sharia courts.