There are two ways that customers can add a CC to tickets they create.
Option One: Email Copy
If you are interacting with the helpdesk mostly through email notifications, then it couldn't be simpler. When you reply to an email notification of a ticket simply CC whoever you want into your response. It doesn't even matter if they are part of your organisation or even a registered user of Typefi. The person will then receive notifications of all future comments on that ticket.
All end users should receive a notification that they've submitted a ticket; just respond to this with the CCs added to the email and your CCs are set up.
Note these added users will not be able to log on to the helpdesk, but they can add comments by replying to their own email notifications.
Option Two: Helpdesk Portal
Sign in to the Helpdesk and add the CC manually; the CC Email option only appears for the customer when they actually click within the comment area. See also the attached screenshot CC_placement.png