Adding one node to SQL XML Explicit results

I would like to add one node only to the bottom of my elements which is the result of an SQL query (for xml explicit).

Here is my query:

SELECT 1 AS Tag,
   NULL AS Parent,
   ROW_NUMBER() OVER
     (
        ORDER BY c.SubCategoryID ASC
     )AS [Customers!1!RowNumber!ELEMENT],
   c.SubCategoryID AS [Customers!1!SubCategoryID!ELEMENT],
   c.Name AS [Customers!1!Name!ELEMENT],
   x.Description AS [Customers!1!Description!ELEMENT], 
   x.Image AS [Customers!1!Image!ELEMENT] 
FROM (SELECT TOP(3) * FROM tSubCategory) c 
CROSS APPLY
(
    SELECT TOP(3) *
    FROM tProduct p
    WHERE c.SubCategoryID = p.SubCategoryID
    ORDER BY p.ProductID DESC
) x 
FOR XML EXPLICIT;

Here is my result:

<Customers>
  <RowNumber>1</RowNumber>
  <SubCategoryID>1</SubCategoryID>
  <Name>John</Name>
  <Description>xtz</Description>
  <Image>ips.png</Image>
</Customers>
<Customers>
  <RowNumber>2</RowNumber>
  <SubCategoryID>1</SubCategoryID>
  <Name>Alex</Name>
  <Description>sdgfgsg</Description>
  <Image>ne2.jpg</Image>
</Customers>

At the bottom of the above result I would like to add one node only:

<Test>
   <Test>1</Test>
</Test>

How would I do that? Also how can I enclose all of my above results into something like:

<AllResults>
</AllResults>