XSLT using a sibling node to generate xml

I have the following xml

<FRA>
   <Id>USD Libor Futures</Id>
<FRA>

I would like the following output

    <FRA>
      <Id>USD Libor Futures</Id>
      <ModifyMktData srcid="USD Libor Futures Convexity" optype="add" srctype="spread" dsttype="rate"/>
   </FRA>

I am using the following xslt:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://ift.tt/tCZ8VR"
    xmlns:msxsl="urn:schemas-microsoft-com:xslt" exclude-result-prefixes="msxsl"
>
  <xsl:output method="xml" indent="yes"/>  

    <xsl:template match="@* | node()">  
        <xsl:copy>
            <xsl:apply-templates select="@* | node()"/>
        </xsl:copy>
    </xsl:template>

  <xsl:template match="FRA/PriceBasis">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()"/>
    </xsl:copy>
    <xsl:variable name="fraid" select="Id"/>
    <ModifyMktData>
      <Update srccontractid="{$fraid} Convexity" optype="add" srctype="Spread" dsttype="Price"/>
    </ModifyMktData>
  </xsl:template>
</xsl:stylesheet>

I am essentially looking to reuse the Id in the attribute for ModifyMktData. Obviously the xslt I have does not work as I would like it to. Thanks in advance.