Sort specific xml nodes - xslt

Question

In the below XML, I need to sort only a specific segment - attrGroupMany name="allergenRelatedInformation" based on the grand child values. And the rest of the XML should be generated as it is with just this segment sorted.
FDA
BIG 8
So all allergenSpecificationAgency that has "FDA" and allergenSpecificationName has "BIG 8" should come before "FDA" and "TREE_NUTS". Please suggest how to achieve this in XSLT. Thanks.
<ns:MT_TradeItemsExport xmlns:ns="test">
<Header version="2.1">
<CreationDateTime>2017-02-09T14:19:03.566Z</CreationDateTime>
<MessageID>0072745000010_9f9cd85e-6d30-4152-a51f-d8491df45486</MessageID>
</Header>
<Payload>
<ItemRegistration>
<attr name="numberOfServingsPerPackage">4.0</attr>
</ItemRegistration>
<attrGroupMany name="organicClaim">
<row>
<attr name="organicTradeItemCode">2</attr>
<attrMany name="organicClaimAgencyCode">
<value>6</value>
</attrMany>
</row>
</attrGroupMany>
<attrGroupMany name="allergenRelatedInformation">
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">BIG 8</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">AC</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">BIG 8</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">AE</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">BIG 8</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">AF</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">BIG 8</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">AM</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">BIG 8</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">AN</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">BIG 8</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">AP</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">BIG 8</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">AY</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">TREE_NUTS</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">TN</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
<row>
<attr name="allergenSpecificationAgency">FDA</attr>
<attr name="allergenSpecificationName">BIG 8</attr>
<attrGroupMany name="allergen">
<row>
<attr name="allergenTypeCode">UW</attr>
<attr name="levelOfContainmentCode">FREE_FROM</attr>
</row>
</attrGroupMany>
</row>
</attrGroupMany>
</Payload>

Answer 1

You can use xsl:perform-sort or xsl:apply-templates together with xsl:sort, to sort the row children use
<?xml version="1.0" encoding="UTF-8" ?>
<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="attrGroupMany[#name ='allergenRelatedInformation']">
<xsl:copy>
<xsl:apply-templates select="#*"/>
<xsl:apply-templates select="row">
<xsl:sort select="attr[#name = 'allergenSpecificationAgency']"/>
<xsl:sort select="attr[#name = 'allergenSpecificationName']"/>
</xsl:apply-templates>
</xsl:copy>
</xsl:template>
</xsl:transform>
http://xsltransform.net/ejivdHR