Is it possible to report on agents in a different group than the Support group they are in? For example, I currently have our agents grouped by function, is it possible to group the reporting of agent tickets by their manager?
You can only use the group attribute to show what Support group an agent is assigned to.
As a workaround, create a custom user field or add a tag in agent profiles to designate which manager they have. Then you can report on that custom user field or tag. Learn more about reporting on tags in this article: Reporting with tags. Learn more about reporting on custom fields in this article: Reporting with custom fields.
Another workaround is to create a custom attribute based on existing attributes such as Assignee name or Assignee email address. By using groups or sets attributes you can group ticket assignees according to managers and use this custom attribute for reporting. Learn more in this article: Organizing values by groups and sets.