Retaining OCG / Layers When Merging PDFs

if PDF_NewPDFLib(PDFLib, True) then begin
  i := 1;
  while (i <= Files2Merge.Count) do begin
    PDFLib.LoadFromFile(Files2Merge[i - 1], ''); { Load Existing File }
    PDFLib.SelectDocument(PDFLib.GetDocumentID(1)); { Select 'Blank' Document }
    PDFLib.CopyPageRanges(PDFLib.GetDocumentID(2), '1'); { Copy Page 1 from existing to 'blank' }
    PDFLib.RemoveDocument(PDFLib.GetDocumentID(2)); { Remove existing from list }
    Inc(i);
  end;
  PDFLib.DeletePages(1, 1); { Delete blank page }
  PDFLib.SaveToFile(MergeMaster);
end;