Add binary Image to existing PDF using iTextSharp in ASP.Net

I spent a whole night trying to add the QR code as image to the uploaded pdf in the literal control where it is being displayed, but could not as the QR code only shows when the PDF file is downloaded; the uploaded PDF file in the literal control does not show. I followed the article you shared to me and tried the example in my test project.

After uploading a PDF file and click a button to navigate to another page, I want the QR code in image control to be added or attached to the uploaded PDF file from previous page and will be shown in the Literal control?

Here is what I tried. I tried to use the code in the BindCardAndQR method, so that when the page loads the QR code image will be added to the uploaded PDF. Actually, the QR code image shows when the PDF downloads but in a white background, different from the uploaded PDF file.

How can I add the QR code image to the uploaded PDf file?

   protected void Page_Load(object sender, EventArgs e)
   {
           BindCardAndQR();
   }
 
   private void BindCardAndQR()
   {
       if (Session["paperinv"] != null)
       {
           int id = Convert.ToInt32(Session["paperinv"]);
           // Binding PDF file in Literal control
           string embed = "<object data=\"{0}{1}\" type=\"application/pdf\"></object>";
           ltEmbed.Text = string.Format(embed, ResolveUrl("Handler.ashx?Id="), id);
 
           // This is where I Bind Image1 control for the QR code generated
           byte[] QRBytes = GetQRCodeBytes(Server.MapPath("~/PDFprint.aspx") + "?Id=" + id);
           Image1.ImageUrl = "data:image/jpg;base64," + Convert.ToBase64String(QRBytes);
 
           byte[] imageBytes = GetQRCodeBytes(Server.MapPath("~/PDFprint.aspx") + "?Id=" + id);
           iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(imageBytes);
 
           using (System.IO.MemoryStream memoryStream = new System.IO.MemoryStream())
           {
               Document document = new Document(PageSize.A4, 10f, 10f, 10f, 0f);
               PdfWriter writer = PdfWriter.GetInstance(document, memoryStream);
               document.Open();
               document.Add(image);
               document.Close();
               byte[] bytes = memoryStream.ToArray();
               memoryStream.Close();
 
               Response.Clear();
               Response.ContentType = "application/pdf";
               Response.AddHeader("Content-Disposition", "attachment; filename=Invoice.pdf");
               Response.ContentType = "application/pdf";
               Response.Buffer = true;
               Response.Cache.SetCacheability(HttpCacheability.NoCache);
               Response.BinaryWrite(bytes);
               Response.End();
           }
       }
   }
   public byte[] GetQRCodeBytes(string url)
   {
       //QR code is generated here
       QRCodeEncoder encoder = new QRCodeEncoder();
       Bitmap bi = encoder.Encode(url);
       MemoryStream tmpSteam = new MemoryStream();
       bi.Save(tmpSteam, ImageFormat.Jpeg);
       return tmpSteam.ToArray();
   }