But I need to use only XSLT 1.0

<xsl:template match="order">
  <xsl:copy>
    <xsl:apply-templates select="@* | node()"/>
    <xsl:variable name="ordernumber" select="order_number"/>
    <xsl:for-each select="$doc2">
      <xsl:apply-templates select="key('order', $ordernumber)/amount"/>
    </xsl:for-each>
  </xsl:copy>
</xsl:template>

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

    =================
    Merge 2 xmls : Loop through one xml and get elements from second xml

    I have 2 xmls(Orders_Part1.xml,Orders_Part2.xml). I have to build the
    3rd xml ( Orders.xml) .