I'm not an expert on copyright law but I DO know a little bit about patent law and have been told by a good patent lawyer that the analogy is appropriate. A patent is INVALID if the patent does not name the actual inventors. Similarly, a copyright is invalid if it does not name the true authors of the song.

The Bear Family set of the complete Carter Family contains the work of Dr. Charles Wolfe and his graduate students who were often able to track down the actual authors of those songs copyright by AP Carter and assigned to that nice Mr. Peer. The Bear Family book was put out with the blessing of Joe and Janette Carter and I think it contains the Carter Family descendants' imprimatur and Nihil Obstat.

   I therefore believe it unnecessary to pay a licensing fee for a Certer Family song misleadingly copyrighted by AP Carter. YMMV