title: Prism Unity - EventAggregator hierarchy
body: <p>i have a problem with EventAggregator, on how make it work, i show a sample application where i have 4 projects:</p>
  
  <p>-Shell
  -Module 'Order'
  -Module 'Customer'
  -Module 'Customer references'
  -Shared (global event aggregator)</p>
  
  <p>Assume that i want to add a new Order, inside my order form (Module.Order) i have a combobox with customers, and a button that open another form to create a customer (Module.Customer) and i want that when i create my customer, the combobox inside the order form reload</p>
  
  <p>I can manage this with that</p>
  
  <p>OrderForm</p>
  
  <pre><code>   private void AddCustomerExecute(object Dialog)
      {
          DialogVisibility = System.Windows.Visibility.Collapsed;
  
          _unityContainer.RegisterInstance&lt;string&gt;("RegionName", M_G_O_ListModule._RegionDialog);
  
          _eventAggregator.GetEvent&lt;UIX_GlobalEvent.PassParameter&gt;().Subscribe(ReloadCustomers);
  
          _moduleManager.LoadModule("M_T_S_CustomersModule");
  
          _shellService.ShowDialogUser(M_G_O_ListModule._RegionDialog, "M_T_S_CustomersModule_Add");
      }
  </code></pre>
  
  <p>CustomerForm</p>
  
  <pre><code>    private void SaveExecute()
      {
          Customer.CustomerCollection.LogAdded = DateTime.Now;
          Customer.CustomerCollection.LogUserID = _userCompany.User.UserID;
  
          _customerRepository.InsertCollection(Customer.CustomerCollection);
  
          _shellService.CloseDialogUser(_regionName, M_T_S_CustomersModule._viewAdd);
  
          _eventAggregator.GetEvent&lt;UIX_GlobalEvent.PassParameter&gt;().Publish(Customer.CustomerCollection.CustomerID);
      }
  </code></pre>
  
  <p>The problem is when from the CustomerForm, i want to add a Reference (Module.CustomerReference) because, if i use the same process, when i save the CustomerReference it reload the combobox inside the order form, because the global event is subscribed</p>
  
  <p>Someone know how can i manage this?
  Thank you</p>