New Twiddle

components.my-child.js

import Ember from 'ember';

export default Ember.Component.extend({
});

components.my-childs-child.js

import Ember from 'ember';

export default Ember.Component.extend({
});

components.my-parent.js

import Ember from 'ember';

export default Ember.Component.extend({
  actions: {
  	someAction() {
    	alert('someAction from parent')
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

{{my-parent}}

templates.components.my-child.hbs

<h2>Child</h2>
<p>==============================</p>
{{my-childs-child onSubmit=(action onSubmit)}}

templates.components.my-childs-child.hbs

<h3>Child's child</h3>
<button {{action onSubmit}}>Submit</button>

templates.components.my-parent.hbs

<h1>Parent</h1>
<p>==============================</p>
{{my-child onSubmit=(action 'someAction')}}

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"
  }
}