I was saying that if your wife had legally adopted her nephew, he would be your stepchild, and could immigrate. He would be your stepchild because he is her legally adopted child. I was not talking about YOU adopting him. The guardianship gets you nothing in terms of his US Immigration. Now that you are married, I don't know that her adoption option still exists. If he is YOUR mutually adopted child, he is not your step child. That immigration route exists, but I'm no expert on it, except that he would need his own petition, just like her natural child. The key issue is that for a step child to immigrate the marriage must occur between you and the legal parent, prior to the child's 18th birthday. Seems that's already done. The problem he is neither her child, your step child, or an adopted child of a US Citizen.