order update

i have an xml that contains 1 orderline of order 100

<order ordernr="100">
  <orderline orderlinenr="1">
     <art>1</art>
  </orderline>
</orderline>

now i want to add new orderlines from an update.xml file
which contains

<order ordernr="100">
  <orderline orderlinenr="2">
     <art>50</art>
  </orderline>
  <orderline orderlinenr="3">
     <art>60</art>
  </orderline>
</orderline>

How do i put these 2 together without loosing the first orderline that is already in this order.

output xml should be

<order ordernr="100">
  <orderline orderlinenr="1">
     <art>1</art>
  </orderline>
  <orderline orderlinenr="2">
     <art>50</art>
  </orderline>
  <orderline orderlinenr="3">
     <art>60</art>
  </orderline>
</orderline>

thanks
pGl
-----------------------------------------------------
Mail.be, Free WebMail and Virtual Office
http://www.mail.be


 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list