Two-way relationships defined as one-way on the backend side

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  child: Ember.computed(function () {
    return this.store.peekRecord('child', '1');
  }),
  
  init () {
    this.store.push({
      data: {
        id: '1',
        type: 'parent',
        attributes: {
          name: 'Stan',
        },
        relationships: {
          children: {
            data: [
              {id: '1', type: 'child'},  
            ]
          }
        }
      }
    });
    
    this.store.push({
      data: {
        id: '1',
        type: 'child',
        attributes: {
          name: 'Steve',
        },
      }
    });
  }
});

models.child.js

import Model from 'ember-data/model';
import attr from 'ember-data/attr';
import { belongsTo, hasMany } from 'ember-data/relationships';

export default Model.extend({
  name: attr('string'),
  parent: belongsTo('parent', {async: false}),
});

models.parent.js

import Model from 'ember-data/model';
import attr from 'ember-data/attr';
import { belongsTo, hasMany } from 'ember-data/relationships';

export default Model.extend({
  name: attr('string'),
  children: hasMany('child', {async: false}),
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
Child: {{this.child.name}}
<br>
Parent: {{this.child.parent.name}}
<br>
<br>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}