Cloud Sync PDF Annotations via Box.com?

I regularly work with teams of 3-4 people who all need to review and annotate PDFs, and my company runs on box.com. The issue is that when any individual team member saves changes to the original file on box.com, it overwrites any previous changes, instead of merging them.

Is there a way to cloud-sync (merge instead of overwrite) annotations through box.com to the same PDF with multiple users?

I know you can add a box.com account within the Acrobat Reader app, which allows you to browse and access files from that account, however it has the same problem of users overwriting previous versions. From what I can tell, it's not a true cloud sync with simultaneous, merged changes. Also, using the Document Cloud for these PDFs is not an option for our current setup.

I have used third-party vendors that do provide this service (Kami, Xodo, etc.) with Google Drive, but Box.com does not have the same integration. I have been surprised to find Adobe does not have an easy-to-find solution for this... I'd love some help!

—J