Conflict between default Adobe Acrobat DC vs Adobe Acrobat Reader DC for end users.

We have a Citrix environment. Client servers are Windows Servers 2012 r2. The majority of users are using Adobe Acrobat Reader DC. A hand full of users have licenses for Acrobat DC. I have been running into this back and forth battle for default application from the server. Every couple of days a user reports the preview pane is no longer showing PDF's and their append to PDF within outlook is no longer working. From what I have found the Server OS chooses to use the last PDF application installed/Repaired as its main application for the preview pane. This is fine, however when Acrobat reader users report the issue. A tech will repair an acrobat reader, this switches the default application. Then the Acrobat DC users have broken append/preview pane functionality. This goes back and forth, never really being solved. Any advice on how to fix this?