Xml formatting structure not staying the same after appending

[bbt2d]

I am working with a xml file. I have appended to an existing sample file, but the formatting is off and some of the xml elements are missing. What I am working toward is appending to it 10 times just changing the number for the element D100 but keep the same data I have just appened for D100 number 2.

Here is the sample xml file I am using

<flp:Tab xmlns:flp="http://www.w3.org/2001/flp"   Title="Testing">
  <flp:Form Number="0" id="1005" />
  <flp:Rev Time="2013-01-21T15:08:00">
    <flp:Author Name="Brad" Aid="15" />
  </flp:Rev>
  <flp:Designs Id="D100">
    <flp:D100 Number="1">
      <flp:Code>A</flp:Code>
      <flp:Documented>true</flp:Documented>
      <flp:Note>In Process</flp:Note>
      <flp:Testers>
        <flp:Tester Name="David">
          <flp:Titles>
            <flp:Title Number="0" Name="Entry 1">
              <flp:Start>Begin</flp:Start>
              <flp:Finish>End</flp:Finish>
            </flp:Title>
          </flp:Titles>
        </flp:Tester>
      </flp:Testers>
      <flp:TestGivers>
        <flp:TestGiver Name="James" />
      </flp:TestGivers>
      <flp:IsRequired>true</flp:IsRequired>
      <flp:IsOptional>false</flp:IsOptional>
    </flp:D100>
  </flp:Designs>
</flp:Tab>

Here is my C# Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Xml;

namespace AppendX
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            XmlDocument doc = new XmlDocument();
            doc.Load("C:\\Desktop\\Temp.xml");

            XmlNamespaceManager namespaces = new XmlNamespaceManager(doc.NameTable);
            namespaces.AddNamespace("flp", "http://www.w3.org/2001/flp");

            XmlNode nextNode = doc.SelectSingleNode("/flp:Tab/flp:Designs", namespaces);

            XmlElement D100 = doc.CreateElement("flp", "D100", "http://www.w3.org/2001/flp");
            D100.SetAttribute("Number", "2");

            XmlElement Code = doc.CreateElement("flp", "Code", "http://www.w3.org/2001/flp");
            Code.InnerText = "B";
            D100.AppendChild(Code);

            XmlElement Documented = doc.CreateElement("flp", "Documented", "http://www.w3.org/2001/flp");
            Documented.InnerText = "false";
            D100.AppendChild(Documented);

            XmlElement Note = doc.CreateElement("flp", "Note", "http://www.w3.org/2001/flp");
            Note.InnerText = "Complete";
            D100.AppendChild(Note);

            XmlElement Tester = doc.CreateElement("flp", "Tester", "http://www.w3.org/2001/flp");
            Tester.SetAttribute("Name", "John");
            D100.AppendChild(Tester);

            XmlElement Title = doc.CreateElement("flp", "Title", "http://www.w3.org/2001/flp");
            Title.SetAttribute("Number", "0");
            Title.SetAttribute("Name", "Ronald");
            D100.AppendChild(Title);

            XmlElement Start = doc.CreateElement("flp", "Start", "http://www.w3.org/2001/flp");
            Start.InnerText = "Begin";
            D100.AppendChild(Start);

            XmlElement Finish = doc.CreateElement("flp", "Finish", "http://www.w3.org/2001/flp");
            Finish.InnerText = "End";
            D100.AppendChild(Finish);

            XmlElement TestGiver = doc.CreateElement("flp", "TestGiver", "http://www.w3.org/2001/flp");
            TestGiver.SetAttribute("Name", "Jeremy");
            D100.AppendChild(TestGiver);

            XmlElement IsRequired = doc.CreateElement("flp", "IsRequired", "http://www.w3.org/2001/flp");
            IsRequired.InnerText = "true";
            D100.AppendChild(IsRequired);

            XmlElement IsOptional = doc.CreateElement("flp", "IsOptional", "http://www.w3.org/2001/flp");
            IsOptional.InnerText = "false";
            D100.AppendChild(IsOptional);

            nextNode.AppendChild(D100);

            doc.Save("test2.xml");
        }
    }
}

Here is the new xml file

<flp:Tab xmlns:flp="http://www.w3.org/2001/XMLSchema" Title="Testing">
  <flp:Form Number="0" id="1005" />
  <flp:Rev Time="2013-01-21T15:08:00">
    <flp:Author Name="Brad" Aid="15" />
  </flp:Rev>
  <flp:Designs Id="D100">
    <flp:D100 Number="1">
      <flp:Code>A</flp:Code>
      <flp:Documented>true</flp:Documented>
      <flp:Note>In Process</flp:Note>
      <flp:Testers>
        <flp:Tester Name="David">
          <flp:Titles>
            <flp:Title Number="0" Name="Entry 1">
              <flp:Start>Begin</flp:Start>
              <flp:Finish>End</flp:Finish>
            </flp:Title>
          </flp:Titles>
        </flp:Tester>
      </flp:Testers>
      <flp:TestGivers>
        <flp:TestGiver Name="James" />
      </flp:TestGivers>
      <flp:IsRequired>true</flp:IsRequired>
      <flp:IsOptional>false</flp:IsOptional>
    </flp:D100>
    <flp:D100 Number="2">
      <flp:Code>B</flp:Code>
      <flp:Documented>false</flp:Documented>
      <flp:Note>Complete</flp:Note>
      <flp:Tester Name="John" />
      <flp:Title Number="0" Name="Ronald" />
      <flp:Start>Begin</flp:Start>
      <flp:Finish>End</flp:Finish>
      <flp:TestGiver Name="Jeremy" />
      <flp:IsRequired>true</flp:IsRequired>
      <flp:IsOptional>false</flp:IsOptional>
    </flp:D100>
  </flp:Designs>
</flp:Tab>

As you can see the formatting is different after appending the new data. I am also missing some elements like Titles and the closing tags are different for some like Title. How can I preserve the formatting form the original document. Thanks!