Enable 2 separate role allocation lists in the user profile (primary & secondary roles)

Having the ability to allocate roles in 2 separate lists would enable roles to be allocated as a primary role or roles i.e. main job, and secondary role or roles i.e. interested in, which would effectively be a means to 'subscribe' to process notifications.

The secondary role could be controlled by the user themselves as well in the User management page.

The content of the notification email could be segregate by primary and secondary roles so the user can see which updates affect them directly and those that they have an interest in.