How to Read, Merge two DataSets from two Xml files & write it to a new Xml file

    XmlTextReader readerOne = new XmlTextReader("C:\\generated.xml");
    XmlTextReader readerTwo = new XmlTextReader("C:\\your-file.xml");

    DataSet dsOne = new DataSet();
    dsOne.ReadXml(readerOne);

    DataSet dsTwo = new DataSet();
    dsTwo.ReadXml(readerTwo);

    dsOne.Merge(dsTwo);
    dsOne.WriteXml("C:\\CompleteResource.xml");
    Console.WriteLine("Merge completed");

Reference link: 

http://stackoverflow.com/questions/11394624/inject-one-xml-file-in-the-other-merge-two-xml-files-in-visual-studio-2010