Docotic.Pdf library can be used to split and merge PDF documents in .NET.
You can append one PDF document to another whenever you need to combine
documents. And, of course, the library can extract or copy PDF
pages from an existing document to a new one.
You can add new pages to PDF documents or remove existing ones with the help of the library.
Take a look at samples that show how to add new pages and insert or remove
existing PDF pages.
You can also change order of pages in your PDF documents.