rest – POSTing a nested object – returning the created nested object inside the parent

Suppose that we have a Post resource (this is just a dummy example):

GET /api/posts/1

{
  "id": 1,
  "header": null,
  "content": null
}

And now we’d like to create a Header inside the Post#1.

POST /api/posts/1/header

{
  "color": "blue",
  "title": "Some title"
}

Now, is it okay for the POST request above to return the following response?

{
  "id": 1,
  "header": {
    "id": 1,
    "color": "blue",
    "title": "Some title"
  },
  "content": null
}

So, basically, a Header was created inside the Post and returned as part of the Post.

Also, if we need to GET the header for Post#1:

GET api/posts/1/header

 {
   "id": 1,
   "color": "blue",
   "title": "Some title"
}

So here only the Header is returned.