Is a Laqeet (foundling child) a legal heir of their deceased adaptor?

Question 11: In 1370 A.H., my father saved a child whom he found wrapped in a cloth and sheltered by rocks at the top of a mountain in the desert. My mother looked after him and breastfed him without her having a child of her own at that time. However, during the two years of breastfeeding, she became pregnant. This child whom my father called Ma`tooq was raised and brought up with us. At the present time, he is an army sergeant and my parents have passed away. My father has bequeathed that this person should inherit along with us. He is on good terms with the whole family. Is he allowed to inherit from our father with us? Is he considered a Mahram (unmarriageable relative)for my mother and her daughters, taking into consideration that Ma`tooq was raised with us until he became adult and got a job? I hope that Your Eminence advises us on the inheritance and his relation with us. May Allaah protect you!

Answer: First, your father and mother are to be thanked for what they did; taking care of this Laqeet (foundling) until he grew up. Second, the breastfeeding that makes the child a Mahram means giving five or more feedings in the child’s first two years. If your mother breastfed this child in this manner, he becomes her milk son, and he becomes a milk brother to her children. Allaah (Exalted be He) says, Forbidden to you (for marriage) are: your mothers, your daughters to His saying …your foster milk suckling sisters Allaah (Exalted be He) also says, The mothers shall give suck to their children for two whole years, (that is) for those (parents) who desire to complete the term of suckling It has been authentically reported that the Prophet (peace be upon him) said,Wet-nursing makes unlawful what consanguinity makes unlawful. It has been proven that `Aa’ishah (may Allaah be pleased with her) said, It was revealed in the Qur’aan that ten known times of breastfeeding prohibit marriage then it was abrogated (and substituted) by five known times of breastfeeding, and the Prophet (peace be upon him) died while it was likewise.read more here.