my discogs script can do that
/t/9226/1
when you are at step 6 of the installation guide there, use the following settings:
DISCOGS_LABEL = contentgroup
all other DISCOGS_... fields = no
DISCOGS~TRACK_OPTION: LEAVE TRACK EMPTY? = yes
DISCOGS~TRACK_OPTION: LEAVE MASTER TRACK EMPTY? = yes
you can choose how to deal with more than one label in this field:
TEXT OPTION: MULTI LABEL: MULTIVALUE TAG (= YES)/ONLY FIRST (= NO)/SEPERATE BY: (WRITE CHARACTERS)