have a following xml 
<param>
    <product_name>ABC</product_name>
    <lcns>
      <lcns1>
          <ext>1000</ext>
          <lcns>text1</lcns>
      </lcns1>
      <lcns2>
          <ext>40</ext>
          <lcns>text2</lcns>
      </lcns2>
      <lcns3>
          <lcns>text3</lcns>
      </lcns3>
    </lcns>
</param>

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1. How can I Insert new entry with lcns4 to this xml 
      <lcns4>
                     <ext>10</ext>
          <lcns>text4</lcns>
      </lcns3>

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2. How can I edit existance entry ,for example 
      <lcns2>
          <ext>50</ext>
          <lcns>new text2</lcns>
      </lcns2>

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All other entries should be stay as it

In reply to How to edit and insert new elements in XML by lazam786

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