Murdos recently added a new report that highlights releases that have disc ids that will be discarded during the NGS data migration phase because the data is not conclusive enough to be reliably migrated. If you have some time, please help us review this data so we can save as much information when we switch over to NGS.
Thanks for creating that report Murdos!
MetaBrainz Blog 
Surely you could just create an empty release event with the lone DiscID and no other data, no?
How can NGS determine which DiscID matches which one of the several CD release events by the way ?
intgr: That is currently not the case. The conversion script is quite picky — it prefers to be correct than incorrect and make a mess for us all to clean up later.
Maybe I already asked but how can NGS determine which DiscID goes with which release event ?
It doesn’t know, it just copies the DiscID to all CD release events.
Ah ok, thanks Lukz !
BTW, here is a search for discid matching in release annotations that could be used either manual or auto.
http://musicbrainz.org/search/textsearch.html?type=annotation&adv=on&query=%22discid+matching%22