Hello. There was a more elegant solution:
<wpv-loop> <li> [wpv-if par="_wpcf_belongs_cd_id" evaluate="!empty($par)"][wpv-post-title id="$cd"][/wpv-if] [wpv-if par="_wpcf_belongs_dvd_id" evaluate="!empty($par)"][wpv-post-title id="$dvd"][/wpv-if] </li> </wpv-loop>