How can you group by portfolio on a task report? I think this is something you can do in text mode?

The reason I ask is because I am trying to create a visual report that will show the pacing of each milestone with in a project, but each project needs to be grouped within its portfolio. Just to be clear, the team isn't thrilled by the milestone report because they want to be able to see the duration/span of each milestone so they can better understand the pacing for the portfolio. I have attached a screenshot of the report i am constructing. Thanks for the help in advance!