Added extension code

templates/CRM/RelateEntities/Common.tpl

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+<div class="crm-accordion-wrapper crm-search_filters-accordion">
+  <a accesskey="N" href="{crmURL p='civicrm/relatedentities/add' q="action=add&reset=1&entityTable=$entityTable&entityId=$entityId"}" class="button"><span><i class="crm-i fa-plus-circle"></i> {ts}New Entity relation{/ts}</span></a>
+</div>
+</br></br>
+{include file="CRM/common/enableDisableApi.tpl"}
+{foreach from=$relatedEntities item="relatedEntity" key="entityRef"}
+<h3>{ts}{$relatedEntity.label}{/ts}</h3>
+<table id='related-entities' class="related-entities-selector-{$entityTable}-{$entityId} crm-ajax-table"
+data-ajax="{crmURL p="civicrm/ajax/relatedentities" q="entityTable=$entityTable&entityId=$entityId&entityTableB=$entityRef"}"
+dataref='{$entityRef}'>
+  <thead>
+  <tr>
+    {foreach from=$relatedEntity.columns item="header" key="key"}
+      <th data-data="{$key}" class="crm-related-entities-{$key}">{ts}{$header}{/ts}</th>
+    {/foreach}
+    <th data-data="links" data-orderable="false" class="crm-related-entities-links">&nbsp;</th>
+  </tr>
+  </thead>
+</table>
+</br></br>
+{/foreach}

templates/CRM/RelateEntities/Expand.tpl

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+{crmScript file='js/crm.expandRow.js'}
+{literal}
+<script type="text/javascript">
+  CRM.$(function($) {
+    let rows = {/literal}{$rows|@json_encode}{literal};
+    $('table tr th:first').before('<th></th>');
+    $.each(rows, function(index, value) {
+      $('table tr#financial_type-' + value['id'] + ' td:first').before(value['expand']);
+    });
+  });
+</script>
+{/literal}

templates/CRM/RelateEntities/Form/RelatedEntity.tpl

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+{include file="CRM/Core/Form/EntityForm.tpl"}

templates/CRM/RelateEntities/Page/Tab.tpl

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+{if $action eq 1 or $action eq 2 or $action eq 8}
+   {include file="CRM/RelateEntities/Form/RelatedEntity.tpl"}
+{else}
+<div class="crm-related-entities-{$context}">
+  {include file="CRM/RelateEntities/Common.tpl"}
+</div>
+{/if}