Error: "The node to be inserted is from a different document context"

Question

You need to import the node into the document before appending it:

XmlNode oNode = moDoc.CreateNode(sNodeType, sName, sNamespaceURI);

//necessary for crossing XmlDocument contexts
XmlNode importNode = oParent.OwnerDocument.ImportNode(oNode, true);

oParent.AppendChild(importNode);
return oNode;