I am using the jCombo plugin and attempting to integrate with Eric Hynds' Multiselect widget. I can get both to work independently but so far no luck together. jCombo allows me to auto-populate a series of select boxes:

Code:
<!doctype html>
<html>
<head>
<title>Select Chain</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script src="http://www.prodiven.com/jcombo/jquery.jCombo.js" type="text/javascript" charset="utf-8"></script>
<script>
		$(document).ready(function() {
			//populate select boxes from php files utilizing jCombo plugin
			$("#cats").jCombo("get_cats.php");
			$("#subcats").jCombo("get_subcats.php?id=", { parent: "#cats" } );
			$("#items").jCombo("get_items.php?id=", { parent: "#subcats" } );
		}); //end ready
</script>

</head>
<body>
<select id="cats"></select>
<select id="subcats"></select>
<select id="items"></select>
</body>
</html>
The multiselect allows for checkboxes in the select box:
Code:
<!DOCTYPE html>
<html>
<head>
<title>jQuery MultiSelect Widget Demo</title>
<!--http://www.erichynds.com/examples/jquery-ui-multiselect-widget/demos/#filter-->
<link rel="stylesheet" type="text/css" href="http://www.erichynds.com/examples/jquery-ui-multiselect-widget/jquery.multiselect.css" />
<link rel="stylesheet" type="text/css" href="http://www.erichynds.com/examples/jquery-ui-multiselect-widget/jquery.multiselect.filter.css" />
<link rel="stylesheet" type="text/css" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1/themes/ui-lightness/jquery-ui.css" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js"></script>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1/jquery-ui.min.js"></script>
<script type="text/javascript" src="http://www.erichynds.com/examples/jquery-ui-multiselect-widget/src/jquery.multiselect.filter.js"></script>
<script type="text/javascript" src="http://www.erichynds.com/examples/jquery-ui-multiselect-widget/src/jquery.multiselect.js"></script>
</head>
<body>
<form style="margin:20px 0">
	<p>
		<select multiple="multiple" style="width:370px">
		<option value="red">Red</option>
		<option value="green">Green</option>
		<option value="blue">Blue</option>
		<option value="orange">Orange</option>
		<option value="purple">Purple</option>
		<option value="yellow">Yellow</option>
		<option value="brown">Brown</option>
		<option value="black">Black</option>
		</select>
  </p>
  <p>
		<select multiple="multiple" style="width:370px">
		<optgroup label="test">
			<option value="red">Red</option>
			<option value="green">Green</option>
			<option value="blue">Blue</option>
		</optgroup>
		<optgroup label="foo">
			<option value="orange">Orange</option>
			<option value="purple">Purple</option>
			<option value="yellow">Yellow</option>
			<option value="brown">Brown</option>
			<option value="black">Black</option>
		</optgroup>
		</select>
	</p>
</form>
<script type="text/javascript">
$("select").multiselect().multiselectfilter();
    </script>
</body>
</html>
I want to be able to use these together, but everything I have tried results in an empty select box where the multiselect widget is applied. In the multiselect widget documentation it is mentioned that that you can append an item to the original select box and then refresh the widget. This is what I have so far in the ready function:

Code:
var $list = $("#items").multiselect();
			$("#items").jCombo("get_items.php?id=", { parent: "#subcats" } );
			$list.multiselect("refresh");
Any ideas or advice on how to integrate this would be much appreciated... thanks!