public void InsertDocumentAtMailMerge()
{
// Open the main document.
Document mainDoc = new Document(MyDir + "InsertDocument1.doc");
// Add a handler to MergeField event
mainDoc.MailMerge.FieldMergingCallback = new InsertDocumentAtMailMergeHandler();
// The main document has a merge field in it called "Document_1".
// The corresponding data for this field contains fully qualified path to the document
// that should be inserted to this field.
mainDoc.MailMerge.Execute(
new string[] { "Document_1" },
new string[] { MyDir + "InsertDocument2.doc" });
mainDoc.Save(MyDir + @"\Artifacts\InsertDocumentAtMailMerge.doc");
}