This template is used within the My Events section of the EE4 User Integration add-on, [ESPRESSO_MY_EVENTS]. Currently the original template will only display registrations that are assigned to the current users contact (registrations made using the same details). So if you place a group registration for 5 tickets and provide different details f…

content-espresso_my_events-event_section.template.php

<?php
/**
 * Template for the "event_section" content template for the [ESPRESSO_MY_EVENTS] shortcode
 *
 * Available template args:
 * @type    EE_Event $event  event object
 * @type    string   $your_tickets_title    title for the ticket.
 * @type    int      $att_id                The id of the EE_Attendee related to the displayed data.
 */
$registrations = $event->get_many_related('Registration', array( array( 'ATT_ID' => $att_id ) ) );

//Create a new array that will contain all registrations
$all_registrations_array = array();

//Loop through all registrations and pull in any other registrations within that group
foreach ($registrations as $registration) {
	
	//Check if the current registration is the primary registration (it should be)
	if ( $registration->is_primary_registrant() ) {
		
		//Pull in all of the registrations assigned to the same group as the primary.
		$all_registrations = $registration->transaction()->registrations();

		//Add each of those registrations to the new array.
		if (!empty($all_registrations)) {
			foreach($all_registrations as $single_registration) {
				array_push($all_registrations_array, $single_registration);
			}
		}
	}

}
// Assign the new array containing all registrations in place of the original 
// this is so that the template works without other modifications.
$registrations = $all_registrations_array;
?>
<tr class="ee-my-events-event-section-summary-row">
	<td class="ee-status-strip event-status-<?php echo $event->get_active_status(); ?>"></td>
	<td>
		<a aria-labelledby="<?php printf( __( 'Link to %s', 'event_espresso' ), $event->name() ); ?>" href="<?php echo get_permalink( $event->ID() ); ?>"><?php echo $event->name(); ?></a>
	</td>
	<td>
		<?php
			$venues = $event->venues();
			$venue_content = array();
			foreach ( $venues as $venue ) :
				$venue_content[] = '<a aria-labelledby="' . sprintf( __( 'Link to %', 'event_espresso' ), $venue->name() ) . '" href="' . get_permalink( $venue->ID() ) . '">' . $venue->name() . '</a>';
			endforeach;
			echo implode( '<br>', $venue_content );
			?>
	</td>
	<td>
		<?php espresso_event_date_range('', '', '', '', $event->ID() ); ?> 2
	</td>
	<td>
		<?php echo count( $registrations ); ?>
	</td>
	<td>
		<span class="dashicons dashicons-admin-generic js-ee-my-events-toggle-details"></span>
	</td>
</tr>
<tr class="ee-my-events-event-section-details-row">
	<td colspan="6">
		<div class="ee-my-events-event-section-details-inner-container">
			<section class="ee-my-events-event-section-details-event-description">
				<div class="ee-my-events-right-container">
					<span class="dashicons dashicons-admin-generic js-ee-my-events-toggle-details"></span>
				</div>
				<h3><?php echo $event->name(); ?></h3>
				<?php
				/**
				 * There is a ticket for EE core: https://events.codebasehq.com/projects/event-espresso/tickets/8405 that hopefully
				 * will remove the necessity for the apply_filters() here.
				 */
				?>
				<?php echo apply_filters( 'the_content', $event->description() ); ?>
			</section>
			<?php
			/**
			 * For now this will just grab the first venue related to the event.  However when we move to multiple venues
			 * per event and/or datetime, this could be modified to have the map show all venues and then list them in the right section
			 */
			$venue = reset( $venues );
			if ( $venue instanceof EE_Venue ) :
			?>
				<section class="ee-my-events-event-section-location-map ee-my-events-one-third">
					<?php
						EE_Registry::instance()->load_Helper( 'Venue_View' );
						echo EEH_Venue_View::espresso_google_static_map( $venue );
					?>
				</section>
				<section class="ee-my-events-event-section-location-details ee-my-events-two-thirds">
					<strong><?php echo $venue->name(); ?></strong>
					<?php echo EEH_Venue_View::venue_address( 'multiline', $venue->ID() ); ?>
				</section>
				<div style="clear:both"></div>
			<?php endif; //end venue check ?>
			<section class="ee-my-events-event-section-tickets-list-table-container">
				<h3><?php echo $your_tickets_title; ?></h3>
				<?php if ( $registrations ) : ?>
					<table class="espresso-my-events-table simple-list-table">
						<thead>
							<tr>
								<th scope="col" class="espresso-my-events-reg-status ee-status-strip">
								</th>
								<th scope="col" class="espresso-my-events-ticket-th">
									<?php echo apply_filters(
										'FHEE__content-espresso_my_events__table_header_ticket',
										esc_html__( 'Ticket', 'event_espresso' ),
										$event
									); ?>
								</th>
								<th scope="col" class="espresso-my-events-datetimes-th">
									<?php echo apply_filters(
										'FHEE__content-espresso_my_events__table_header_datetimes',
										esc_html__( 'Dates & Times', 'event_espresso' ),
										$event
									); ?>
								</th>
								<th scope="col" class="espresso-my-events-actions-th">
									<?php echo apply_filters(
										'FHEE__content-espresso_my_events__actions_table_header',
										esc_html__( 'Actions', 'event_espresso' ),
										$event
									); ?>
								</th>
							</tr>
						</thead>
						<tbody>
							<?php foreach( $registrations as $registration ) {
								if ( ! $registration instanceof EE_Registration ) {
									continue;
								}
								$template_args = array( 'registration' => $registration );
								$template      =  'content-espresso_my_events-event_section_tickets.template.php';
								EEH_Template::locate_template( $template, $template_args, true, false );
							}
							?>
						</tbody>
					</table>
				<?php else : ?>
					<div class="no-tickets-container">
						<p>
							<?php echo apply_filters(
									'FHEE__content-espresso_my_events-no_tickets_message',
									esc_html__( 'You have no tickets for this event', 'event_espresso' ),
									$event
							           ); ?>
						</p>
					</div>
				<?php endif; ?>
			</section>
		</div>
	</td>
</tr>

Reference:
https://eventespresso.com/topic/ee4-show-all-datetimestickets-user-registered-for-on-espresso_my_events/
https://eventespresso.com/topic/registration-numbers-and-ticket-number-confusion/