Select list showing items not in model

I have a model for my groups, which is basically the following fields:

• Name


• Users

I am populating a list in my template with the following

{{view "Ember.Select" content=model.users  optionValuePath="content.id" optionLabelPath="content.name" attributeBindingds="size" size="5"}}

I load all users in the system in the controller, as so:

export default Ember.Controller.extend({
    users: [],

    init: function () {
        this._super();

        this.set('users', this.store.find('user'));
    })
})

All users are populated as follows:

{{view "Ember.Select" content=users  optionValuePath="content.id" optionLabelPath="content.name" attributeBindingds="size" size="5" }}

What is the most appropriate way of filtering the second select to contain only users that aren't in the first select - that is, to show users that do not exist in model.users