Alter Existing Routes

To alter an existing route, we can use hook_init(). In this example we'll make the built in user.login route a child of our app's home page.

/**
 * Implements hook_init().
 */
function my_module_init() {

  // Make the user login page's base route our home page.
  dg.router.saveAsChildRoute('user.login', 'my_module.home');

}

This will have a link to the User Login page appear in the Primary Local Tasks when viewing our app's home page.