how repeat specific tag with child after last tag XML

Question

hi

my xml samle:

 

<Y>
  <x>
    <PH>
      <SQ>3SQ>
      <ND>4524115ND>
      <SN>545SN>
      <PC>545PC>
      <PG>54PG>
      <PP>5400PP>
      <PS>44500PS>
      <IS>0IS>
    PH>
    <BY>
      <MH>
        <MG>4545MG>
        <MP>25000MP>
        <MI>15000MI>
        <MS>0MS>
      MH>
    BY>
  x>
Y>

 i have create text box for each tag and i have one button (save) to create X tag and chiled.

 

i want add new button "add MH" to add MH tag and child ( MG,MP,MI,MS) after last MH tag

i wang after click button update xml sample this:

 

<Y>
  <x>
    <PH>
      <SQ>3SQ>
      <ND>4524115ND>
      <SN>545SN>
      <PC>545PC>
      <PG>54PG>
      <PP>5400PP>
      <PS>44500PS>
      <IS>0IS>
    PH>
    <BY>
      <MH>
        <MG>4545MG>
        <MP>25000MP>
        <MI>15000MI>
        <MS>0MS>
      MH>
      <MH>
        <MG>123MG>                i want add this MH tag
        <MP>5000MP>
        <MI>5000MI>
        <MS>0MS>
      MH>
    BY>
  x>
Y>

 my code for Button Save is:

 

private void button1_Click(object sender, EventArgs e){
 XmlNode customernode = xmldoc.CreateNode(XmlNodeType.Element, "x", null);
    XmlNode tartibnode = xmldoc.CreateNode(XmlNodeType.Element, "SQ", null);
    XmlNode datevisitnode = xmldoc.CreateNode(XmlNodeType.Element, "ND", null);
    XmlNode bimenode = xmldoc.CreateNode(XmlNodeType.Element, "SN", null);
    XmlNode nezamnode = xmldoc.CreateNode(XmlNodeType.Element, "PC", null);
    XmlNode pezeshknode = xmldoc.CreateNode(XmlNodeType.Element, "PG", null);
    XmlNode mablaghkolnode = xmldoc.CreateNode(XmlNodeType.Element, "PP", null);
    XmlNode mablaghbimarnode = xmldoc.CreateNode(XmlNodeType.Element, "PS", null);
    XmlNode mablaghbimenode = xmldoc.CreateNode(XmlNodeType.Element, "IS", null);
    XmlNode khedmatnode = xmldoc.CreateNode(XmlNodeType.Element, "MG", null);
    XmlNode sahmekolnode = xmldoc.CreateNode(XmlNodeType.Element, "MP", null);
    XmlNode sahmebimenode = xmldoc.CreateNode(XmlNodeType.Element, "MI", null);
    XmlNode sahmebimarnode = xmldoc.CreateNode(XmlNodeType.Element, "MS", null);
    XmlNode tagkolnode = xmldoc.CreateNode(XmlNodeType.Element, "PH", null);
    XmlNode tagkhedmatnode = xmldoc.CreateNode(XmlNodeType.Element, "MH", null);
    XmlNode tagbynode = xmldoc.CreateNode(XmlNodeType.Element, "BY", null);

    tartibnode.InnerText = txtsq.Text;
    datevisitnode.InnerText = txtnd.Text;
    bimenode.InnerText = txtsn.Text;
    nezamnode.InnerText = txtpc.Text;
    pezeshknode.InnerText = txtpg.Text;
    mablaghkolnode.InnerText = txtpp.Text;
    mablaghbimarnode.InnerText = txtps.Text;
    mablaghbimenode.InnerText = txtis.Text;
    khedmatnode.InnerText = txtmg.Text;
    sahmekolnode.InnerText = txtmp.Text;
    sahmebimenode.InnerText = txtmi.Text;
    sahmebimarnode.InnerText = txtms.Text;

tagkolnode.AppendChild(tartibnode);
tagkolnode.AppendChild(datevisitnode);
tagkolnode.AppendChild(bimenode);
tagkolnode.AppendChild(nezamnode);
tagkolnode.AppendChild(pezeshknode);
tagkolnode.AppendChild(mablaghkolnode);
tagkolnode.AppendChild(mablaghbimarnode);
tagkolnode.AppendChild(mablaghbimenode);

tagkhedmatnode.AppendChild(khedmatnode);
tagkhedmatnode.AppendChild(sahmekolnode);
tagkhedmatnode.AppendChild(sahmebimenode);
tagkhedmatnode.AppendChild(sahmebimarnode);

    tagbynode.AppendChild(tagkhedmatnode);
    customernode.AppendChild(tagkolnode);
    customernode.AppendChild(tagbynode);
    rootnote.AppendChild(customernode);

    xmldoc.Save(xmlpath);  }

 for Button update this code but not work:

private void button2_Click(object sender, EventArgs e)
       {

           xmldoc.Load(xmlpath);
           rootnote = xmldoc.DocumentElement;

           XmlNode khedmatnode = xmldoc.CreateNode(XmlNodeType.Element, "MG", null);
           XmlNode sahmekolnode = xmldoc.CreateNode(XmlNodeType.Element, "MP", null);
           XmlNode sahmebimenode = xmldoc.CreateNode(XmlNodeType.Element, "MI", null);
           XmlNode sahmebimarnode = xmldoc.CreateNode(XmlNodeType.Element, "MS", null);
           XmlNode tagkhedmatnode = xmldoc.CreateNode(XmlNodeType.Element, "MH", null);
           XmlNode tagbynode = xmldoc.CreateNode(XmlNodeType.Element, "BY", null);


           khedmatnode.InnerText = txtmg.Text;
           sahmekolnode.InnerText = txtmp.Text;
           sahmebimenode.InnerText = txtmi.Text;
           sahmebimarnode.InnerText = txtms.Text;

           tagkhedmatnode.AppendChild(khedmatnode);
           tagkhedmatnode.AppendChild(sahmekolnode);
           tagkhedmatnode.AppendChild(sahmebimenode);
           tagkhedmatnode.AppendChild(sahmebimarnode);

           tagbynode.AppendChild(tagkhedmatnode);

           tagbynode.InsertAfter(tagkhedmatnode , tagkhedmatnode);



           xmldoc.Save(xmlpath);
       }

 tank you