Custom grouping to show all projects assigned to a specific designer

Hi there! 

In one of my project reports I've created a custom column to show who the specific designer is on each project using the below formula in text mode: 

displayname=Designer
listdelimiter=
listmethod=nested(projectUsers).lists
textmode=true
type=iterate
valueexpression=IF(CONTAINS("Designer",{user}.{role}.{name}),{user}.{name})
valueformat=HTML

What I would like to do next, is be able to group those projects by the specific designer so we can see all projects assigned to Designer A, for example. I know we can leverage the workload balancer for similar details, but I was hoping to accomplish this view within a specific report. So far I have been unsuccessful in identifying if/how this can be done. 

Any thoughts? 

TIA

Emmi