How do I load a component into one Angular 4 parent router-outbound?

I have an Angular 4 app with app.component.html as -

<app-sidebar></app-sidebar>
<app-topbar></app-topbar>
<router-outlet></router-outlet>

      

        
        
        
      

    

Two routes for two different components -

• Parent - /test
  
  for TestComponent
• Child - /test/:id
  
  for TestChildComponent

TestComponent is displayed in <router-outlet></router-outlet>

app.component.html .

I would like the TestChildComponent to also be loaded into the same version of the app for the specified URL. Is it possible? Or, is there any other way to structure it?