Reporting for Internal Groups/Collaborators

We have Agents assigned the ticket as primary ticket holder. We then add a collaborator to the ticket via the internal groups field and select the individual. Is there a way to report on the collaborators work?

We have some instances where the collaborators part is complete but the ticket needs to remain open for the Agent to finalize things. This causes discrepancies between the collaborators work and reporting.

Example: Report on “closed” for the Internal Group/Collaborator and have a separate report for closed for Agent.