Searching examples could not find a way to add page numbering using MigraDoc to existing PDFs.
So I have:
PdfDocument outPdf = new PdfDocument()
var pdfFile = PdfReader.Open(new MemoryStream(pdfData), PdfDocumentOpenMode.Import))
CopyPages(pdfFile, outPdf)
How to add here a Section, Paragraph, Footer/Header?