on select change render dynamic form

I'm wondering what the best way to handle dynamic forms in ember.

On select change on existing model on the main form, I need to bring up a "sub-form" right underneath based on the selection. Afterwards I need to submit the sub-form and on success callback submit the main form.

I'm not using the Ember-data (atleast not at this point) only custom ajax calls.

I have the on select change event being passed to the controller, this is fine. But then I need to submit the sub-form which can vary.

I'm relatively new to ember so I'm not sure what the best way to approach this in Ember. Seems like one way is to dynamically generate the models?

A rough example if possible would be appreciated.