How to enable clients super user to interact with all tickets?

Hi there!

I'm working for an IT service and support company and we are about to onboard a new client to work with us through Zendesk Support. The clients employees will open tickets for their support requests in our Zendesk through Email. 

Through Zendesk Guide and "Organisation Requests", we are able to give the supervisor (the clients inhouse IT responsible employee) the ability to see all the tickets opened by his organization. Thats nice. 

In Zendesk Guide, the clients supervisor is also able to interact with his own tickets, and the tickets where he's CC. But, unfortunately, hes not able to interact with the "Organization requets". 

We are looking to find a way or setup, which allows the clients supervisor not only to see all the tickets of his organization, but also to add public comments to all those tickets. 

What I've tried is turning on "Organization subscription", which sends an Email-Notification to this user for every comment/update made on all the tickets from his org. But, if he replies to one of those emails, his comment is added to the ticket as an internal comment, which is not visible to the requester. 

The only workaround we've found so far, is manually adding the supervisor as CC to all tickets manually. This allows the supervisor to interact with the tickets in Guide, in the "Tickets where I'm CC'ed on" view. But, adding the supervisor as CC manually to every ticket is cumbersome and prone to error. 

One thing would be to place a feature request to have the option to enable to add comments to tickets in the "Organization Request" view, but I wonder if there is another practical way to enable the clients supervisor to be able to add public comments to all tickets without beeing added as CC. 

I figured this requirement might be quite common, so I thought someone reading this might have across a solution for this already. 

Thanks for your thoughts and help :)