The only software that can work with .dmsm files is actually the software in which these files were saved in first place, Roxio Creator. In this case it might be just a matter of recovery or export of playlists, so this might even work even if you do not have all the multimedia data referenced in the projects. But except for that, we do not have any information about any software capable of dmsm to rxp conversion.
Updated: August 1, 2023