Infopath Multi Textbox and OpenXML to generate word document

Question

 Hi,
I'm reading multiple InfoPath Textbox (set to display multiple lines) using OpenXML and generating a word document based on a template collecting data from InfoPath. I'm using following code,  the code gives error in
AddMultiLineText at Paragraph p = sdt.GetFirstChild<SdtContentBlock>().GetFirstChild<Paragraph>(); 
The code actually works when I use only one Multi Textbox but fails if its more than one. I'm quite new to Infopath and OpenXML, I would appreciate some help ASAP as its holding me in my project:
Event Receiver
  public override void ItemAdded(SPItemEventProperties properties)
           try
               this.EventFiringEnabled = false;
               string siteUrl = properties.WebUrl;
               SPListItem item = properties.ListItem;
               SPWeb web = properties.Web;
               SPList lib = web.Lists["DocLib"];
               SPFile file = lib.RootFolder.Files["template.docx"];
               string generatedDoc = "";
               if (file != null)
                   byte[] templateBytes = file.OpenBinary();
                   using (MemoryStream ms = new MemoryStream())
                       ms.Write(templateBytes, 0, (int)templateBytes.Length);
                       byte[] convertedDocBytes = ConvertInfoPathToWord(ms, item.File);
                       generatedDoc = item["LinkFilename"].ToString().Replace("xml", "docx");
                       SPFile newFile =
                         lib.RootFolder.Files.Add(generatedDoc, convertedDocBytes, true);
                       ms.Close();
 private byte[] ConvertInfoPathToWord(MemoryStream ms, SPFile file)
           byte[] bytes = file.OpenBinary();
           using (MemoryStream msInternal = new MemoryStream(bytes))
               XmlDocument doc = new XmlDocument();
               doc.Load(msInternal);
               XPathNavigator root = doc.CreateNavigator();
               root.MoveToFollowing(XPathNodeType.Element);
               string ns = root.GetNamespace("my");
               XmlNamespaceManager nsMgr = new XmlNamespaceManager(new NameTable());
               nsMgr.AddNamespace("my", ns);
                string multiLineText1 = root.SelectSingleNode(
                 "/my:myFields/my:field1", nsMgr).Value;
               string multiLineText2 = root.SelectSingleNode(
                 "/my:myFields/my:field2", nsMgr).Value;
                using (WordprocessingDocument myDoc =
                 WordprocessingDocument.Open(ms, true))
                   MainDocumentPart mainPart = myDoc.MainDocumentPart;
                   List<OpenXmlElement> sdtList = InfoPathToWord.GetContentControl(
                     mainPart.Document, "multilinetext1");
                   InfoPathToWord.AddMultiLineText(multiLineText1, ref sdtList);
                   List<OpenXmlElement> sdtList = InfoPathToWord.GetContentControl(
                     mainPart.Document, "multilinetext2");
                   InfoPathToWord.AddMultiLineText(multiLineText2, ref sdtList);
                    myDoc.Close();
               msInternal.Close();
           return ms.ToArray();
        public static List<OpenXmlElement> GetContentControl(
          Document doc, string name)
            List<OpenXmlElement> list = new List<OpenXmlElement>();
            List<SdtBlock> sdtList = doc.Descendants<SdtBlock>()
              .Where(s => name.Contains(s.SdtProperties.GetFirstChild<SdtAlias>()
              .Val.Value)).ToList();
            if (sdtList.Count == 0)
                List<SdtRun> sdtRunList = doc.Descendants<SdtRun>()
                  .Where(s => name.Contains(s.SdtProperties.GetFirstChild<SdtAlias>()
                  .Val.Value)).ToList();
                foreach (SdtRun sdt in sdtRunList)
                    list.Add(sdt);
            else
                foreach (SdtBlock sdt in sdtList)
                    list.Add(sdt);
            return list;
        public static void AddMultiLineText(
          string multiLineText, ref List<OpenXmlElement> sdtList)
            string[] lines = multiLineText.Split(new char[] { '\n' });
            if (sdtList.Count != 0)
                foreach (OpenXmlElement sdt in sdtList)
                    for (int i = 0; i < lines.Length; i++)
Paragraph p =
                          sdt.GetFirstChild<SdtContentBlock>().GetFirstChild<Paragraph>(); //this ERRORS
                        if (i == 0)
                            InfoPathToWord.WriteText(lines[i], ref p);
                        else
                            Paragraph pNext = sdt.AppendChild((Paragraph)p.Clone());
                            InfoPathToWord.WriteText(lines[i], ref pNext);

Answer 1

Additional Info: multiLineText1 and multiLineText2 are "Plain Text Content Control" in the word template used to create the word document.