What is the ruling on a person remaining attributed to his adoptive father – despite his knowledge of the Ḥadīth: "Whoever knowingly attributes himself to other than his father, Jannah is forbidden for him" – especially since the adoptive father's wife breastfed him and considers him her son, and she has not given birth, along with the difficulty of changing the lineage?

No one is permitted to claim lineage from other than their father. Islam abolished adoption with the Almighty's saying: "Call them by [the names of] their fathers; it is more just in the sight of Allah." Those who have been adopted must change their lineage to their true fathers, if known, or attribute themselves to a general name like "Abdul Rahman" or "Abdul Khaliq." As for the adopted child being nursed by the wife of the adoptive father, this makes her his milk-mother if she nursed him within the two years [of infancy] with recognized suckling. He is permitted to be alone with her and shake her hand, but her status does not reach that of the mother who gave birth to him. As for the adopted girl, if she shared suckling with the questioner's friend from the same woman, then she is his milk-sister. Otherwise, she remains a stranger to him.