moving elemnts from XML FILE to Another XML file

I Have two XML files which have the following elements insite them (the item element and its child only) :

<cat id="computer">
    <item>
        <SN>value</SN>
        <name>value</name>
        <quantity>value</quantity>
        <description>value </description>
        <price>value </price>
    </item>
</cat>
<cat id="Stationery">
    <item>
        <SN>value</SN>
        <name>value</name>
        <quantity>value</quantity>
        <description>value </description>
        <price>value </price>
    </item>
</cat>

//I have here the following code which delete those elements (the item element and its child only).

xmlDoc.Root.Descendants("cat").Where(x => x.Attribute("id").Value == "computer")
      .Descendants("item").Where(x => x.Element("SN").Value.Trim() == Dropdownlist.Text)
      .Remove();
xmlDoc.Save(@"YourXML.xml");

what I want is to copy these elements from first xml file to the second xml file before deleting them. how can I do such process using LINQ ?