Request for Scheduling update

Our GBM Project Managers would like to request a Scheduling feature on the Scheduling tab under People. Instead of swapping out roles at the project level (i.e. every task assigned to GBM Copywriter switch to Grace Hilty), they want to swap roles at the Parent Task Level. For a specific subset of tasks you would ideally be able to swap out one user to replace the Copywriter generic role for ONLY that subset of tasks, and for another subset of tasks you could assign another user as the Copywriter.