field_get_items / value when creating new content
One option would be to take advantage of states (see states and/or forms reference).

Here is an example... It's by no means perfect but hopefully it will give you an idea of how states work:

$options_1 = array('Option A', 'Option B', 'Option C');
$options_2 = array('Option D', 'Option E', 'Option F');
$element['overzicht_producten'][] = array(
  '#type' =&gt; 'select',
  '#title' =&gt; t('Overzicht producten'),
  '#options' =&gt; $options_1,
  '#states' =&gt; array(
    'visible' =&gt; array(
      // To make this select menu visible, type "Visible1" (no quotes) into the "searchfield" box.
      ':input[name="searchfield"]' =&gt; array('value' =&gt; 'Visible1'),
    ),
  ),
);
$element['overzicht_producten'][] = array(
  '#type' =&gt; 'select',
  '#title' =&gt; t('Overzicht producten'),
  '#options' =&gt; $options_2,
  '#states' =&gt; array(
    'visible' =&gt; array(
      // To make this select menu visible, type "Visible2" (no quotes) into the "searchfield" box.
      ':input[name="searchfield"]' =&gt; array('value' =&gt; 'Visible2'),
    ),
  ),
);


Hope that helps... :)