If the adoptive father dies intestate, the inheritance should also be distributed according to legal inheritance. If it had been distributed according to legal inheritance at that time, the house should have a share. The pile of laws upstairs has been made clear, so I won't say much.
But I still feel something is wrong. Under normal circumstances, after the death of the decedent, the division of the estate should be transferred to the heir within a reasonable period of time. In other words, from the legal point of view, A's adoptive father's inheritance should be inherited, and how much should be distributed to whom should have been decided long ago. I need you to add one more point: after the death of adoptive father A, did the adoptive mother directly transfer the property to the adoptive mother or one of her own children? How to distribute the adoptive father's other personal property, such as deposits? Did A get any inheritance or something when his adoptive father died? In short, the more detailed the whereabouts of the adoptive father's property after his death, the better. Also, how many years have passed since the adoptive father died?
In addition, the statement that "the adoptive father died without a will, so it is not in the hands of the adoptive mother" is wrong.
Okay, that's enough. I assume here that A will give some advice on whether he will turn against his foster mother and other brothers.
Article 1 of the Supreme People's Court's Opinions on Several Issues Concerning the Implementation of the Inheritance Law of People's Republic of China (PRC), inheritance begins when the decedent dies physically or is declared dead. But you also said that there was no division of property from the beginning of inheritance. In other words, A, who is now an adopted son, should be assigned to the inheritance.
Article 8 of the Inheritance Law stipulates that the time limit for bringing a lawsuit for disputes over inheritance rights is two years, counting from the day when the successor knows or should know that his rights have been infringed. However, if more than 20 years have passed since the beginning of the succession, no lawsuit may be brought. That is to say, if the property of A's adoptive father has been divided by his adoptive mother or other brothers, the divided part A cannot be recovered. The same is true of real estate.
But you said that the house was not transferred to anyone after A's adoptive father died. Assuming that the house has a real estate license, and the real estate license is the name of A's adoptive father, A can now request the people's court to "continue the inheritance procedure", or take the house for himself on the grounds that "other legal heirs (adoptive mother, adopted brothers and sisters) have not claimed the right to inherit property since the beginning of inheritance, and the statute of limitations has expired". However, if the real estate license is in the name of A's foster mother, or A's foster mother has a certain share, A needs to return the share of the foster mother to the foster mother in cash in order to occupy the house.
If the case is submitted to the court, the court will have greater discretion on this issue. It can be considered that inheritance stopped before the stage of dividing property and continues the inheritance process now; It can also be considered that the successor other than A has exceeded the limitation of action, and A can occupy and obtain the house. In short, everyone in A has a share, just a big share and a small share.
All of the above are presumptions that the property is under the name of A's adoptive father. I still have a question. If A's adoptive father's property is not divided and inherited, then if the property is in A's adoptive father's name, why should A's adoptive mother sell the house? Did the adoptive mother "embezzle" the adoptive father's inheritance without knowing it?