I was notified of an RFE yesterday by text. I called this morning to get more information and they have my fiance as being previously married (common law). They basically want proof that he is no longer in a marriage. The common law marriage was to his son mother. They are no longer living together. They haven't lived together for 2 years. Do I need him to go ahead a get the certificate of nonimpediment. Will that be sufficient proof that he has single and free to marry?