First post, so forgive any ignorance displayed in this question:
I work for a publisher and we publish a journal that has a close relationship with a conference; an important community in this field. Authors of full papers at the Conference are given the option of submitting to the Journal. We have worked out an integrated review process whereby the reviews performed for the conference count towards the journal’s review process. This makes it efficient and pleasing to all parties. The articles are published in the journal but they contain a statement that acknowledges that the article derives from the conference. The journal is online-only, OA and continuous, so the conference-derived articles are not published in a special issue, but they are curated on the journal website on a special collection page dedicated to the conference.
In the past, the same conference has published its proceedings independently: some years as a single PDF in a repository, in other years via a professional publisher. When published independently, the automatically generated citation style for the proceedings as a whole from the repository (and for the individual articles in the professionally published case) have contained the proceedings title as the title of the publication (e.g. 9th Conference of X, 2021).
When the articles from the Conference are published within the journal, the citation style of course just refers to the journal as the publication.
My question is whether there is a way of referring both to the journal and the conference within a single citation, without breaking rules with regards to citation standards, metadata or machine readability.
For example, is there a precedent within citation styles for a sub-journal category (such as special section)? If so, could this be used in the scenario that I describe?