How to dynamically Prepopulate / Prefill addressfields
I cant find any reference of hook_form_entityform_alter if it is available you will want to take out the hook part and replace this with you module name.

I have re written the code using hook_form_alter. You will need to replace $address1 etc with your own code.

function letter_addresses_form_alter(&amp;$form, &amp;$form_state, $form_id) {

// Ensure, we're updating field info on the correct entity type
//This needs to be more specific incase more entity forms are created
if ($form_id == 'yourformname_entityform_edit_form') {

// Only do this for a new, not-yet updated entityform -NB might need a 'return' here
if (!isset($form['#entity']-&gt;is_new)) {
//Populate the entityform addressfield with values from the user addressfield
$address1 = "address1";
$address2 = "address2";
$county = "county";
$postcode = "postcode";
$form['field_address'][LANGUAGE_NONE][0]['#address']['thoroughfare'] = $address1;
$form['field_address'][LANGUAGE_NONE][0]['#address']['premise'] = $address2;
$form['field_address'][LANGUAGE_NONE][0]['#address']['locality'] = $county;
$form['field_address'][LANGUAGE_NONE][0]['#address']['administrative_area'] = $county;
$form['field_address'][LANGUAGE_NONE][0]['#address']['postal_code'] = $postcode;
  }
}