This is a @NateWr kind of thing.
Some of our journals like to have several editors working with submissions. The new discussion feature in OJS3 is of course a great way to communicate between the editors/section editors but starting a new discussion means that you have to add every participant one by one.
What would you think if besides the "Add user" button there would be a "Add group" button, which would add for example all assigned section editors as participants to the discussion? This would save a lot of clicks.