invites

ability.rb

class Ability
  include CanCan::Ability

  def employee_abilities(user)
    # [ code ]
    # I imagine the invite abilities being set just like the group
    # viewer abilities and supervisor abilities are set now. 
    supervisor_abilities(user) if user.employee.supervisor?
    group_viewer_abilities(user)
    invite_abilities(user)
  end

  def invite_abilities(user)
    # [ code ] 
  end 
end

schema

Invites
  user_id
  invited_user_id
  permission_level