Nested addon CSS not merged into vendor.css - ember.js

Question

I have an addon, my-addon-parent, that depends on a nested addon, my-addon-nested, that specified via the the dependencies property in my-addon-parent's package.json.
When I run the dummy app for my-addon-parent, the nested addon's CSS is imported correctly (I use the included hook to specify the import) and added to the vendor.css file.
However, when including my-addon-parent in an Ember app, the nested addons CSS is not added to the vendor.css file. Is there a hook/setting that I am missing? Below are the package.json for the app and the respective index.js files for the parent and nested addons.
Ember App package.json
{
"name": "my-app",
"version": "0.0.0",
"description": "My App.",
"private": true,
"directories": {
"doc": "doc",
"test": "tests"
},
"scripts": {
"start": "ember server",
"build": "ember build",
"test": "ember test"
},
"repository": "",
"engines": {
"node": ">= 0.10.0"
},
"author": "",
"license": "MIT",
"devDependencies": {
"broccoli-asset-rev": "^2.0.0",
"connect-restreamer": "^1.0.1",
"ember-cli": "0.2.0",
"ember-cli-app-version": "0.3.2",
"ember-cli-babel": "^4.0.0",
"ember-cli-content-security-policy": "0.3.0",
"ember-cli-dependency-checker": "0.0.8",
"ember-cli-htmlbars": "0.7.4",
"ember-cli-ic-ajax": "0.1.1",
"ember-cli-inject-live-reload": "^1.3.0",
"ember-cli-qunit": "0.3.9",
"ember-cli-uglify": "1.0.1",
"ember-data": "1.0.0-beta.15",
"ember-export-application-global": "^1.0.2",
"express": "^4.12.3",
"glob": "^4.5.3",
"morgan": "^1.5.2",
"my-addon-parent": "some/location"
}
}
my-addon-parent index.js
/* jshint node: true */
'use strict';
module.exports = {
name: 'my-addon-parent',
included: function (app) {
this._super.included(app);
app.import('vendor/my-addon-parent/my-addon-parent.css');
}
};
my-addon-nested index.js
/* jshint node: true */
'use strict';
module.exports = {
name: 'my-addon-nested',
included: function (app) {
this._super.included(app);
app.import('vendor/my-addon-nested/my-addon-nested.css');
}
};

Answer 1

This is currently not possible. Details here.