Need help to write xsl code to exclude a complete xml node based on a certain node.

Requirement is to create the output only if FLDVAL is set to X in child node. Since the FLDVAL is not set to X in the 2nd ZSEGMENT1 node, complete node and its child segments should be excluded. But the first ZSEGMENT and its child nodes should be copied as FLDVAL is set to X in that node.

If FLDVAL is not X in all ZSEGMENT1 node, no output should be created.

Attempt currently:

<xsl:stylesheet version="1.0" xmlns:xsl="w3.org/1999/XSL/Transform" xmlns:fo="w3.org/1999/XSL/Format">
  <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes" />
  <xsl:template match="@* | node()">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()" />
    </xsl:copy>
  </xsl:template><!-- Match and output only the ZSEGMENT2 segments meeting the specified condition -->
  <xsl:template match="ZSEGMENT2[FLDNAME='CUSTOM' and FLDVAL='X']]">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()" />
    </xsl:copy>
  </xsl:template>
</xsl:stylesheet>

Input XML

<DELVRY03>
  <IDOC BEGIN="1">
    <EDI_DC40 SEGMENT="1">
      <TABNAM>EDI_DC40</TABNAM>
      <MANDT>111</MANDT>
      <DOCNUM>0000000001234567</DOCNUM>
      <DOCREL>731</DOCREL>
      <RCVPRN>0000001234</RCVPRN>
    </EDI_DC40>
    <ZSEGMENT1 SEGMENT="1">
      <FLD1>value1</FLD1>
      <FLD2>value2</FLD2>
      <ZSEGMENT2 SEGMENT="1">
        <FLDGRP>ABC</FLDGRP>
        <FLDNAME>CUSTOM<< /FLDNAME>
            <FLDVAL>X</FLDVAL>
      </ZSEGMENT2>
    </ZSEGMENT1>
    <ZSEGMENT1 SEGMENT="1">
      <FLD1>value1</FLD1>
      <FLD2>value2</FLD2>
      <ZSEGMENT2 SEGMENT="1">
        <FLDGRP>ABC</FLDGRP>
        <FLDNAME>CUSTOM<< /FLDNAME>
            <FLDVAL></FLDVAL>
      </ZSEGMENT2>
    </ZSEGMENT1>
  </IDOC>
</DELVRY03>

Output XML

<DELVRY03>
  <IDOC BEGIN="1">
    <EDI_DC40 SEGMENT="1">
      <TABNAM>EDI_DC40</TABNAM>
      <MANDT>111</MANDT>
      <DOCNUM>0000000001234567</DOCNUM>
      <DOCREL>731</DOCREL>
      <RCVPRN>0000001234</RCVPRN>
    </EDI_DC40>
    <ZSEGMENT1 SEGMENT="1">
      <FLD1>value1</FLD1>
      <FLD2>value2</FLD2>
      <ZSEGMENT2 SEGMENT="1">
        <FLDGRP>ABC</FLDGRP>
        <FLDNAME>CUSTOM<< /FLDNAME>
            <FLDVAL>X</FLDVAL>
      </ZSEGMENT2>
    </ZSEGMENT1>
  </IDOC>
</DELVRY03>