Problems with PHP/XML/XSL - php

Question

I am trying to figure out what I can do to create a code that appends data in my XML file not rewrite the XML file continuously.
I need to be able to save all the form entries and as of right now every time the form is submitted. it creates a new XML file and erases the old one.
This may be really easy to fix or I am just really dumb but I have looked at DOM syntax and do not see what I could change to change the outcome.
// define configuration file name and path
$configFile = 'abook.xml';
// if form not yet submitted
// display form
if (!isset($_POST['submit'])) {
// set up array with default parameters
$data = array();
$data['name'] = null;
$data['email'] = null;
$data['caddress'] = null;
$data['city'] = null;
$data['state'] = null;
$data['zipcode'] = null;
$data['phone'] = null;
$data['pug'] = null;
$data['comment'] = null;
$data['subscribe'] = null;
// read current configuration values
// use them to pre-fill the form
if (file_exists($configFile)) {
$doc = new DOMDocument();
$doc->preserveWhiteSpace = false;
$doc->load($configFile);
$address = $doc->getElementsByTagName('address');
foreach ($address->item(0)->childNodes as $node) {
$data[$node->nodeName] = $node->nodeValue;
}
}
In between is a PHP form and validation code and at the end I use XML tags again:
// generate new XML document
$doc = new DOMDocument();
// create and attach root element <configuration>
$root = $doc->createElement('addressbook');
$configuration = $doc->appendChild($root);
// create and attach <oven> element under <configuration>
$address = $doc->createElement('address');
$configuration->appendChild($address);
// write each configuration value to the file
foreach ($config as $key => $value) {
if (trim($value) != '') {
$elem = $doc->createElement($key);
$text = $doc->createTextNode($value);
$address->appendChild($elem);
$elem->appendChild($text);
}
}
// format XML output
// save XML file
$doc->formatOutput = true;
$doc->save($configFile) or die('ERROR: Cannot write configuration file');
echo 'Thank you for filling out an application.';
}
I am really new at this so I am sorry if my code is pretty messy.
The second part I am dealing with an XSL file which I have linked to my XML file but no matter what syntax I have used to transform, nothing works to save it in a table.
Again, I don't know if this could be caused by the way I have set up my PHP to write the XML.