Proper Handling of hasMany/belongsTo in Ember Data with Rails Persistence - ruby-on-rails

Question

I have an Ember.js app (1.0.0-rc.3) using Ember Data (Rev 12) to persist to a Rails backend. On the client side, I have two models that have a one-to-many relationship:
App.Child = DS.Model.extend(
name: DS.attr('string')
parent: DS.belongsTo('App.Parent')
App.Parent = DS.Model.extend(
name: DS.attr('string')
children: DS.hasMany('App.Child')
)
I have configured my store to expect JSON from Rails that embeds relationships rather than side-loading them:
App.Store = DS.Store.extend(
revision: 12
adapter: DS.RESTAdapter.extend(serializer: DS.RESTSerializer.extend(init: ->
#_super()
#map "App.Child",
parents:
embedded: "always"
))
)
And then I have a form for creating a new App.Child record. In the childNewController for the new App.Child form view, I create a new App.Child and a new App.Parent as follows:
#transaction = #get('store').transaction()
#set('content', #transaction.createRecord(App.Child, {}))
#set('content.parent', #transaction.createRecord(App.Parent, {}))
I have textfields bound to the various attributes of both child and parent. When I click the save button on the form, an action in the childNewController commits the changes with #transaction.commit().
THE PROBLEM
When the transaction is committed, Rails receives two JSON POST requests—one to the ParentController with JSON that looks like:
{"parent"=>{"name"=>"William"}}
...and a second POST to the ChildController with JSON that looks like:
{"child"=>{"name"=>"Henry", "parent"=>{"name"=>"William"}}}
Now the Rails ChildController and ParentController are both trying to save the new parent.
Ideally, the request to the ParentController would go away, since I don't want it, and it lacks sufficient information to establish a relationship with the child. I would simply ignore the request to ParentController, but Ember Data is expecting a response from the server.
Another option would be to let ParentController save the new parent, and then ChildController could look up the newly-saved parent record and create the linkage to the new child record. The problem is that the sequence of the two requests is unpredictable.
Because of this sequencing issue, I tried putting Parent.find_or_create_by_name(parent_name) in both Rails controllers, on the theory that if one controller has already created the new parent, the other would only execute a lookup of that new parent record. However, this resulted in duplicate parent records!
I'm really at a loss to understand why Ember Data insists on pushing duplicate JSON representations of the parent to the backend. I'm sure it's a simple configuration error on my part.
Update
I found an acceptable workaround for now by chaining the commits:
newParent = #transaction.createRecord(App.Parent, {name: parentName})
currentChild = #get('content') # we assigned a new App.Child to the childNewController in the new child route's controller setup
currentStore = #get('store')
newParent.one('didCreate', this, ->
now = new Date()
transaction = currentStore.transaction()
transaction.add currentChild
transaction.commit()
transaction = null
)
newParent.get('transaction').commit()
#transaction = null
Is there a better way to do this?