merging XML tables to add records?

Hi,

I'd like to know if this is possible to merge XML tables (same structure)? I need to add some records in my grid, and keep the previous ones?
Is it better to use JSON in this case?

Thank you in advance

I've finally found a solution to merge 2 XML tables with Sarissa library.
http://dev.abiss.gr/sarissa/

<script type="text/javascript" src="sarissa.js"></script>

...

var req = new AW.HTTP.Request;
req.setURL(url);
req.setAsync(false); 

req.response = function(data) {
        var newXMLdata = this.getResponseXML();
        var currentXML = dataTable.getXML();
        var rootFrom = newXMLdata.getElementsByTagName("root")[0];
        var rootTo = currentXML.getElementsByTagName("root_list")[0];

        Sarissa.copyChildNodes(rootFrom, rootTo, true);

        dataTable.setXML(currentXML);
};

req.request();
  Hope it can help someone else...