Is the son of zinā considered a brother to the children of the man who committed zinā with his mother and then married her, given that their mother is also his mother and nursed them all, despite his different lineage from them?

If a woman commits adultery and gives birth to a child, the child is attributed to her alone. This does not mean that the bond between him and his maternal siblings is severed, for the bond of motherhood is ثابت (established) whether the child is born of adultery or a valid marriage. The child born of adultery is treated like maternal siblings in matters of kinship ties (silat al-rahim), inheritance, and so forth. As for his relationship with his father from adultery, it is severed.