function MergeStreamsViaMergeDocument(FirstStream, SecondStream,

    OutputStream: TMemoryStream): Integer;

  var

    doc1, doc2: Integer;

  begin

    with TQuickPDF.Create do

    try

      FirstStream.Seek(0, soFromBeginning);

      LoadFromStream(FirstStream);

      doc1 := SelectedDocument;

      SecondStream.Seek(0, soFromBeginning);

      LoadFromStream(SecondStream);

      doc2 := SelectedDocument;

      SelectDocument(doc1);

      MergeDocument(doc2);

      OutputStream.Seek(0, soFromBeginning);

      SaveToStream(OutputStream);

    finally

      Free;

    end;

  end;