I would think that he has some stake, or claim to his father's estate if there is any. Unless his father stipulated, in his will, that his child was to be ecluded. My biographical father just gave away a valuable car collection to my sister. I do not speak to my father because he was a hateful crature. He had promised two of the vehicles to my children. I told them that they were better off without his binding gifts. He has a large nest egg left over that I would think will also go to my sister and I, again, remain ambivalent. My biological mother is also on her last legs. I have talked to the executor of her estate and requested that her sizable inheritance be left, in trust, to my children. I have never needed anyone's help, worked hard all my life, and am quite proud that I do not need anything from anyone.