Append XML string block WITH NAMESPACE REF to existing XmlDocument in .NET

Question

I have an xml document (XmlDocument) which looks like this...

<stuff xmlns:n="hhtp://tempuri.com/">
</stuff>

... and a "fragment" (string) which looks like this

<things>
    <thing n:type="info">
    </thing>
</things>

I want to "inject" the fragment into the main document.

How?

(HINT: You can't use XmlDocumentFragment because the namespace 'n' isn't declared in the fragment, and the object model complains about this - throwing an 'unknown namespace' error even though the resultant document will be perfectly valid.)