Avoid showing new model itself

I have got a form to create a new Model called Route. In the form is a select field, called takeover, showing all Routes and the user can select one to get an relationship to the selected Route. My problem is that the newly created Route is even selectable in the select field, because I simply return 'this.get('store').findAll('routes');'. How can I remove the new Model from the selection, because it is not possible to create a relationship to itself