Backbone form model updating

Question

I am using a backbone form that is created using a backbone model. When a piece of the form changes in the view I need to update an attribute of the schema of the model that created the form.

I'm getting the value of the change event when the model updates its data from one of the other form fields like so:

this.form.on('change:someFormField', function(form, someFormFieldSelector) {
    var value = someFormFieldSelector.getValue();

Now what I feel like should happen is that I am able to update the other form field based on the value I have captured above like so:

    form.fields.anotherFormField.useFormFieldsFunction(value);
});

Alas, that does not work because the field is already rendered. Really all I can think of doing besides this would be to re-set the backbone model and blast away the form to rebuild it. Or to stop using the model so that I have easier access to my form elements. I'm not sure which to do.

tl;dr using backbone forms and want a way to update form fields and the model without blasting it away first.