Retrieve hasMany child records in route

I have the following route:

/projects/5/files

I read in the API that using find() and findAll() will automatically update any templates that use their results when records are pushed to the store. How can I do that with the child file records?

I currently have this in my projects/files.js route:

model() {
  return this.modelFor('project').get('attachments')
}

This works on first load but won't update when adding records to the store.