Question

I want to merge two XmlDocuments by inserting a second XML doc to the end of an existing Xmldocument in C#. How is this done?

Answer 1

Something like this:

foreach (XmlNode node in documentB.DocumentElement.ChildNodes)
{
    XmlNode imported = documentA.ImportNode(node, true);
    documentA.DocumentElement.AppendChild(imported);
}

Note that this ignores the document element itself of document B – so if that has a different element name, or attributes you want to copy over, you’ll need to work out exactly what you want to do.

EDIT: If, as per your comment, you want to embed the whole of document B within document A, that’s relatively easy:

XmlNode importedDocument = documentA.ImportNode(documentB.DocumentElement, true);
documentA.DocumentElement.AppendChild(importedDocument);

This will still ignore things like the XML declaration of document B if there is one – I don’t know what would happen if you tried to import the document itself as a node of a different document, and it included an XML declaration… but I suspect this will do what you want.