If "match" else

In XSLT I often match nodes using the following command

<xsl:template match="*[local-name() = 'Proposal']/*[local-name() = 'ApplicationData']">

which would get the nodes from

<?xml version="1.0" encoding="utf-8"?><?xfa generator="XFA2_4" APIVersion="2.8.9029.0"?>
    <xdp:xdp xmlns:xdp="http://ift.tt/1fDw6Kc" timeStamp="2013-03-01T09:48:58Z" uuid="3e3468da-104d-4532-8077-0dc001ca166b">
       <xfa:datasets xmlns:xfa="http://ift.tt/1c7vSVL">
          <xfa:data>
             <Proposal xmlns="http://ift.tt/1uwmo2V" Version="">
                 <oneapp:ApplicationData xmlns:oneapp="http://ift.tt/1uwmo2V">
                        <oneapp:TreesHedgesWales/>
                        <oneapp:OtherLowCarbonEnergy/>
                 </oneapp:ApplicationData>
             </Proposal>
         ...

matching

<oneapp:ApplicationData xmlns:oneapp="http://ift.tt/1uwmo2V">
      <oneapp:TreesHedgesWales/>
      <oneapp:OtherLowCarbonEnergy/>
 </oneapp:ApplicationData>

How could I determine whether ApplicationData existed, and if not, insert it?