In our journal we’ve had and will have even more cases where structures and characteristics of edited volumes and journal issues are mixed. Generally, most of our “special issues” have editors or could be compared to edited volumes. Ideally these editors should be added on the issue level, like authors to articles, and are then added to articles in the metadata (DC, OAI, DOI, coins, doaj, etc.).
See https://forum.pkp.sfu.ca/t/ojs-2-4-8-1-assigning-editors-to-issues/20148 for the preceding discussion.