MACROMEDIA FLASH MX 2004-ACTIONSCRIPT LANGUAGE Reference page 1014

var clone:XMLNode = doc2.firstChild.cloneNode(true);
doc1.appendChild(clone);
trace ("doc1: " + doc1); // output: doc1: <root />
trace ("doc2: " + doc2); // output: doc2: <root />
// create a new node to append to root node (named clone) of doc1
var newNode:XMLNode = doc1.createElement("newbie");
clone.appendChild(newNode);
trace ("doc1: " + doc1); // output: doc1: <root><newbie /></root>
1014 Chapter 2: ActionScript Language Reference