I need to add element "REFERENCE" for every parent node after STATUS element.
<ORDER> <DETAIL> <STATUS>1</STATUS> <TYPE>1</TYPE> </DETAIL> <DETAIL> <STATUS>2</STATUS> <TYPE>3</TYPE> </DETAIL> </ORDER>

Code:
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
            doc.Load(filename);
...