I have a similar list for the day job, but this is really helpful for anyone curious about who's publishing comics, and who owns which imprints. It's not comprehensive, but it's a solid starting point that she'll likely expand.
For libraries, it's also helpful for knowing which are Big 5 imprints that will make it harder to get their ebooks at a fair price. 😐
https://www.graphiclibrary.org/info-postings/publishers-and-imprints-info-for-librarians