How to include a XML file within another XML

I would like to know how to include an external XML within another XML (calling some XSL).

I created one hundred HTML page. Each page have 3 links to XML. Each XML file have a link to a XSL (the XSL is load in a fancy lightbox) and the same XML database.

I do not want to duplicate the database structure in each XML. That is why I would like to create a link from the “parent” XML to the “database” XML (to ease updates).

This is a sample of my code :

The HTML page :

<a class="fancybox fancybox.iframe" href="profil1.xml" title="Profil 1"><img class="profil" src="design/profil1.png" /></a>
<a class="fancybox fancybox.iframe" href="profil2.xml" title="Profil 2"><img class="profil" src="design/profil2.png" /></a>
<a class="fancybox fancybox.iframe" href="profil3.xml" title="Profil 3"><img class="profil" src="design/profil3.png" /></a>

The first XML who contains the link to XSL :

<?xml version="1.0" standalone="no" ?>
<?xml-stylesheet type="application/xml" href="profil1.xsl"?>

The XML database I would like to link to the first XML :

<catalogue>
<domain type="dom1">
<data type="aaa">
    <profil>profil 1</profil>
    <avail>no</avail> 
</data>
<data type="bbb">
    <profil>profil 2</profil> 
    <avail>no</avail> 
</data>
<data type="bbb">
    <profil>profil 3</profil>
    <avail>no</avail> 
</data> 
</domain>

<domain type="dom2">
<data type="aaa">
    <profil>profil 1</profil>
    <avail>no</avail> 
</data> 
<data type="bbb">
    <profil>profil 1</profil>
    <avail>yes</avail> 
</data> 
</domain>
</catalogue>

I failed to create an include or an "ENTITY data SYSTEM "data.xml"". Is there a solution who works with IE, FF and Chrome ?

Thank you in advance for your help,