1-current-router.js

// router.js

import Ember from 'ember';

import config from './config/environment';

let Router = Ember.Router.extend({
  location: config.locationType
});

let accountRoutes = function(router) {
  router.route('account', { path: 'account' }, function() {
    this.route('password', { path: 'change_password' });
    this.route('preferences');
  });
};

Router.map(function() {
  accountRoutes(this);
  this.route('admin', { path: 'admin' }, function() {
    accountRoutes(this);
  });
});

export default Router;

2-concerns-sketch-router.js

// router.js

import Ember from 'ember';

import config from './config/environment';

let Router = Ember.Router.extend({
  location: config.locationType
});

Router.concern('account', function() {
  this.route('account', { path: 'account' }, function() {
    this.route('password', { path: 'change_password' });
    this.route('preferences');
  });  
});

Router.map(function() {
  this.concerns('account');
  this.route('admin', { path: 'admin' }, function() {
    this.concerns('account');
  });
});

export default Router;