<?php

/**
 * Module to prepopulate season price list with rooms
 */

/**
 * Implements hook_form_FORM_ID_alter(&$form, &$form_state)
 */

function mymodule_form_seasonal_prices_node_form_alter(&$form, &$form_state){

    // Load all of the room node ids into an array
    $node_type = "room";
    $result = db_query("SELECT nid FROM node WHERE type = '%s' ", $node_type);
    $nids = array();
  while ($obj = db_fetch_object($result)) {
    $nids[] = $obj->nid;
  }

  // Set the form state to include each room
  foreach($nids as $nid){
    $form_state->field_collection_you_want_to_edit[] = $nid
  }
}