Add prefixed Nodes to a specific prefixed child Node C#

I'm stuck making a huge XML and trying to add prefixed Nodes to a specific prefixed nodes.

I have tried to use

srcXML.Element("importManifest").Element("cargaDes").Add( from el in NewNode.Elements() select el)

without luck.

I have this:

<soapenv:Body>
<web:importManifest>
  <web:cargaDes>
    <web:ArrayPallet>
      <web:boxes>
        <web:Color>color</web:Color>
        <web:Commodity>Comm</web:Commodity>
        <web:CustomerBrand>Brand</web:CustomerBrand>
        <web:CustomerReference>CusReference</web:CustomerReference>
        <web:FolioClient>FolioClient</web:FolioClient>
        <web:FolioFisico>FolioFis</web:FolioFisico>
        <web:Grower>Grw</web:Grower>
        <web:OriginOfPackage>OriofPack</web:OriginOfPackage>
        <web:PalletFolio>PalletFolio</web:PalletFolio>
        <web:PlaceOfOrigen>PlaceOrig</web:PlaceOfOrigen>
        <web:Presentation>Presenta</web:Presentation>
        <web:QuantityOfBoxes>QtyBoxes</web:QuantityOfBoxes>
        <web:Size>size</web:Size>
      </web:boxes>
      <web:ManifestFolio>ManFolio</web:ManifestFolio>
      <web:PalletFolio>PalletFolio2</web:PalletFolio>
    </web:ArrayPallet>     
  </web:cargaDes>
</web:importManifest>

I want This:

<soapenv:Body>
<web:importManifest>
  <web:cargaDes>
    <web:ArrayPallet>
      <web:boxes>
        <web:Color>color</web:Color>
        <web:Commodity>Comm</web:Commodity>
        <web:CustomerBrand>Brand</web:CustomerBrand>
        <web:CustomerReference>CusReference</web:CustomerReference>
        <web:FolioClient>FolioClient</web:FolioClient>
        <web:FolioFisico>FolioFis</web:FolioFisico>
        <web:Grower>Grw</web:Grower>
        <web:OriginOfPackage>OriofPack</web:OriginOfPackage>
        <web:PalletFolio>PalletFolio</web:PalletFolio>
        <web:PlaceOfOrigen>PlaceOrig</web:PlaceOfOrigen>
        <web:Presentation>Presenta</web:Presentation>
        <web:QuantityOfBoxes>QtyBoxes</web:QuantityOfBoxes>
        <web:Size>size</web:Size>
      </web:boxes>
      <web:ManifestFolio>ManFolio</web:ManifestFolio>
      <web:PalletFolio>PalletFolio2</web:PalletFolio>
    </web:ArrayPallet>

    <web:ArrayPallet>
      <web:boxes>
        <web:Color>color</web:Color>
        <web:Commodity>Comm</web:Commodity>
        <web:CustomerBrand>Brand</web:CustomerBrand>
        <web:CustomerReference>CusReference</web:CustomerReference>
        <web:FolioClient>FolioClient</web:FolioClient>
        <web:FolioFisico>FolioFis</web:FolioFisico>
        <web:Grower>Grw</web:Grower>
        <web:OriginOfPackage>OriofPack</web:OriginOfPackage>
        <web:PalletFolio>PalletFolio</web:PalletFolio>
        <web:PlaceOfOrigen>PlaceOrig</web:PlaceOfOrigen>
        <web:Presentation>Presenta</web:Presentation>
        <web:QuantityOfBoxes>QtyBoxes</web:QuantityOfBoxes>
        <web:Size>size</web:Size>
      </web:boxes>
      <web:ManifestFolio>ManFolio</web:ManifestFolio>
      <web:PalletFolio>PalletFolio2</web:PalletFolio>
    </web:ArrayPallet>

  </web:cargaDes>
</web:importManifest>

Hope you can help me, many thanks!