Hello, I am wondering how I can use groups to manage teams of people, but not be able to assign tasks to the group.

I just want to be able to manage a team such as:

Marketing or Accounting 

but right now, when I add the Marketing group to a project, the Marketing group itself becomes an assignment option for the project rather than just individuals of that group. I know I can work arounds this by not using groups for projects, but am wondering if there is still a way to do this.