What is the ruling on a sterile man willing all his wealth to his adopted daughter, whom he registered in his name, due to the absence of kinship ties between him and his siblings?

Islam has prohibited adoption and nullified it with the Almighty's saying: "Nor has He made your adopted sons your [real] sons." Therefore, what you have done by adopting this girl is a sin for which repentance is obligatory, and it does not entail any legal rulings such as inheritance, financial support (nafaqah), or prohibition of marriage (hurmat al-musaharah). This attribution must be changed. In contrast, Islam has encouraged the care of foundlings (luqata'), and showing kindness to them is an act of piety and closeness to Allah. The endowment of this money to her is valid if its conditions are met. It is advised to show kindness to your siblings and not deprive them of beneficence, as it is more worthy than showing kindness to a stranger, being both charity (sadaqah) and maintaining kinship ties (silat ar-rahim).