A functions to build the ticket list by first pulling the attendee's session_id from the DB, then grabbing all the attendee's within that session and looping through them. This is useful for MER registrations..

custom_functions.php

<?php //Please do not include the opening PHP tag if there is already one within the file that is still open.

function espresso_ticket_links_by_session($registration_id, $attendee_id, $multi_reg, $email = FALSE) {
	global $wpdb;
	$sql = "SELECT attendee_session FROM " . EVENTS_ATTENDEE_TABLE;
	if (espresso_is_primary_attendee($attendee_id) != true) {
		$sql .= " WHERE id = '" . $attendee_id . "' ";
	} else {
		$sql .= " WHERE registration_id = '" . $registration_id . "' ";
	}
	//echo $sql;
	$attendee_session = $wpdb->get_var($sql);
 
	$sql = "SELECT * FROM " . EVENTS_ATTENDEE_TABLE . " WHERE attendee_session = '" . $attendee_session . "' ";
 
	$attendees = $wpdb->get_results($sql);
 
	$ticket_link = '';
	if ($wpdb->num_rows > 0) {
		
		$break = '<br />';
		$group = $wpdb->num_rows > 1 ? sprintf(__('Tickets Purchased (%s):', 'event_espresso'), $wpdb->num_rows).$break : __('Download/Print Ticket:', 'event_espresso').$break;
		
		foreach ($attendees as $attendee) {
			$ticket_url = get_option('siteurl') . "/?download_ticket=true&id=" . $attendee->id . "&r_id=" . $attendee->registration_id;
			if (function_exists('espresso_ticket_launch')) {
				$ticket_url = espresso_ticket_url($attendee->id, $attendee->registration_id);
			}
			$ticket_link .= '<a href="' . $ticket_url . '" target="_blank">' . $attendee->fname . ' ' . $attendee->lname . '</a>' . $break;
		}
		
		if ($email == TRUE){
			$text = '<p>' . $group . $ticket_link .'</p>';
		}else{
			$text = $ticket_link;
		}
		
		return $text;
	}
}