Thanks! That was the hint I needed. Here is what I did which I think might be useful for others. I added a simple substr_count so we don't get URL's deeper than the first level of the website. For my site structure, this is perfect. I'm sure YMMV for others.
about line 188 of function_phpdig_form.php...
Code:
while ($dd_data = mysql_fetch_array($dd_query)) {
++ // limit results to only main URL's - don't get lots of useless stuff
++ if (substr_count($dd_data['path'],"/") <= 1) {
$result['form_dropdown'] .= "<option value='".$dd_data['site_id'].",".$dd_data['path']."'>".$dd_data['site_url'].$dd_data['path']."</option>";
++ }
}