The Collection Maintenance Subcommittee (at its May 10, 2017 meeting) and the ILS Committee (at its June 7, 2017 meeting) (minutes) recently passed some changes to the Videorecordings Searching and Matching Policy, which is available online at http://www.scls.info/ils/policies/cat/linking-searchingandmatching-video-policy.html.
Going forward, Criterion Collection DVD or Blu-ray sets can be circulated together, on the same bib record. This is true even if the sets contain different movies or different productions of the same movie.
This only applies to Criterion Collection sets. Non-Criterion Collection multi-part DVD or Blu-ray sets of different feature films or different productions of the same feature film are still circulated separately, according to the rules outlined in the Videorecordings Searching and Matching Policy.
For more information on The Criterion Collection, see http://www.criterion.com.