Hi I have this problem:

I need to combine two data groups below:

A. conditions:

1. Each release has a unique Id.

2. The two groups have duplicated <doc_number>s. if one <release> in data 
group A has a <doc_number> that is already in data group B, remove that 
entire <release> node in data group A.

3. Certain <release> does not even have a <doc_number>, but there is a 
<doc_number /> tag to represent an empty value. in this case, we keep the 
entire <release> node.

4. insert ";headlines;" into the "display_on" attribute to the <release>.

Current file:

<!-- start of file -->

<releases>

<!-- Data group A -->

<release id="2" name="AB" display_on="headlines;" type="NEWS">

 <doc_number>6</doc_number>

</release>

<release id="4" name="CD" display_on="headlines;" type="NOTICE">

 <doc_number>5</doc_number>

</release>

<release id="6" name="EF" display_on="headlines;" type="ORDER">

 <doc_number>4</doc_number>

</release>

<release id="8" name="GH" display_on="headlines;" type="ORDER">

 <doc_number>3</doc_number>

</release>

<release id="10" name="IJ" display_on="headlines;" type="NOTICE">

 <doc_number>2</doc_number>

</release>

<release id="12" name="KL" display_on="headlines;" type="NOTICE">

 <doc_number />

</release>



<!-- Data group B -->
<release id="14" name="XY" display_on="homepage" type="MEMORANDUM">
 <doc_number>5</doc_number>
</release>
<release id="16" name="MN" display_on="sidepage" type="NOTICE">
 <doc_number>4</doc_number>
</release>
<release id="18" name="OP" display_on="otherpage" type="NOTICE">
 <doc_number>3</doc_number>
</release>
</releases>
<!-- end of file -->
Desired resulting file:
<!-- start of file -->
<releases>
<!-- Data group A -->
<release id="2" name="AB" display_on="headlines;" type="NEWS">
 <doc_number>6</doc_number>
</release>
<release id="10" name="IJ" display_on="headlines;" type="NOTICE">
 <doc_number>2</doc_number>
</release>
<release id="12" name="KL" display_on="headlines;" type="NOTICE">
 <doc_number />
</release>

<!-- Data group B -->

<release id="14" name="XY" display_on="homepage;headlines" 
type="MEMORANDUM">

 <doc_number>5</doc_number>

</release>

<release id="16" name="MN" display_on="sidepage;headlines" type="NOTICE">

 <doc_number>4</doc_number>

</release>

<release id="18" name="OP" display_on="otherpage;headlines" type="NOTICE">

 <doc_number>3</doc_number>

</release>

</releases>

<!-- end of file -->

Right now I have this code written to generate the result, but it only works 
partially.

1. It removes the duplicated <doc_number> from each release, but it does not 
remove the whole release.

2. It does not insert ";headlines;" into the "display_on" attribute to the 
<release>

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
version="1.0">

<xsl:output method="xml" omit-xml-declaration="yes"/>

<xsl:template match="doc_number">

 <xsl:if test="not(string(.))">



 </xsl:if>
 <xsl:if test="not(. = following::fcc_doc_number)">
  <xsl:copy>
   <xsl:apply-templates select="@*|node()"/>
  </xsl:copy>
 </xsl:if>
</xsl:template>
<xsl:template match="@*|node()">
 <xsl:copy>
  <xsl:apply-templates select="@*|node()"/>
 </xsl:copy>
</xsl:template>
</xsl:stylesheet>
Please anyone help out? thank you!

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