xQuery-Extracting distinct elments by attribute

I have below xml,which contains a list of customers and their orders and items in orders,I want to get a list contains distinct values of customers, customer's id is the attribute of "Name":

<customersunion>
  <Customer Name="c2">
    <Order OrderNumber="o1">
      <Item Description="xyz"> i10 </Item>
    </Order>
  </Customer>

 <Customer Name="c3">
    <Order OrderNumber="o1">
      <Item Description="qwe"> i11 </Item>
      <Item Description="mnb"> i12 </Item>
    </Order>
    <Order OrderNumber="o2">
      <Item Description="cfg"> i5 </Item>
    </Order>
 </Customer>

 <Customer Name="c1">
    <Order OrderNumber="o1">
      <Item Description="abc"> i1 </Item>
      <Item Description="def"> i2 </Item>
    </Order>
 </Customer>

 <Customer Name="c4">
    <Order OrderNumber="o1">
      <Item Description="abc"> i1 </Item>
    </Order>
    <Order OrderNumber="o2">
      <Item Description="def"> i2 </Item>
    </Order>
 </Customer>

 <Customer Name=" c2 ">
    <Order OrderNumber=" o1 ">
      <Item Description=" milk "/>
 </Order>
 </Customer>

 <Customer Name=" c10 ">
    <Order OrderNumber=" o1 ">
      <Item Description=" chips greek yogort avacado "/>
    </Order>
 </Customer>

 <Customer Name=" c4 ">
    <Order OrderNumber=" o1 ">
      <Item Description=" tea bags cheese "/>
    </Order>
 </Customer>

 <Customer Name=" c11 ">
    <Order OrderNumber=" o1 ">
      <Item Description=" milk sushi Notebook "/>
    </Order>
 </Customer>

 <Customer Name=" c11 ">
    <Order OrderNumber=" o2 ">
      <Item Description=" grape tomato "/>
    </Order>
 </Customer>

 <Customer Name=" c12 ">
    <Order OrderNumber=" o1 ">
      <Item Description=" bread "/>
    </Order>
 </Customer>
</customersunion>

and below is the result I want to get

<customers>
  <Customer Name="c1">
    <Order OrderNumber="o1">
      <Item Description="abc"> 
       i1
      </Item>
      <Item Description="def"> 
       i2
      </Item>
    </Order>
  </Customer>

  <Customer Name="c2">
    <Order OrderNumber="o1">
      <Item Description="xyz"> 
       i10
      </Item>
    </Order>
  </Customer>

  <Customer Name="c3">
    <Order OrderNumber="o1">
      <Item Description="qwe"> 
       i11
      </Item>
      <Item Description="mnb"> 
       i12
      </Item>
    </Order>
    <Order OrderNumber="o2">
      <Item Description="cfg"> 
       i5
      </Item>
    </Order>
  </Customer>
  <Customer Name="c4">
    <Order OrderNumber="o1">
      <Item Description="abc"> 
       i1
      </Item>
    </Order>
    <Order OrderNumber="o2">
      <Item Description="def"> 
      i2
      </Item>
    </Order>
  </Customer>
  <Customer Name="c10">
    <Order OrderNumber="o1">
      <Item Description="chips">i1</Item>
      <Item Description="greek yogort">i2</Item>
      <Item Description="avacado">i3</Item>
    </Order>
  </Customer>

  <Customer Name="c11">
    <Order OrderNumber="o1">
      <Item Description="milk">i1</Item>
      <Item Description="sushi">i2</Item>
      <Item Description="Notebook">i3</Item>
    </Order>
    <Order OrderNumber="o2">
      <Item Description="grape tomato">i1</Item>
    </Order>
  </Customer>

  <Customer Name="c12">
    <Order OrderNumber="o1">
      <Item Description="bread">i1</Item>
    </Order>
  </Customer>
</customers>

I used follow xQuery

let $customername:=doc("customerunion.xml")/Customer/@Name
for $uniquecustomer in distinct-values($customerunion/customersunion/Customer/@Name)
let $order:=distinct-values($customerunion/customersunion/Customer[Name=$uniquecustomer]/Order)
let $item:=distinct-values($customerunion/customersunion/Customer[Name=$uniquecustomer]/Order/Item)
where $uniquecustomer=$customername
return 
 <customerlib>
    {$uniquecustomer/..}
    {
    for $o in $order return $o
    }
    {
    for $i in $item return $i
    }
 </customerlib>

However, I got 0 line of result, could you help me to modify to xQuery then I can get the desired result?