Admin Bookings Summary Page - Event ID

/*
 * paste in your theme functions.php
 * after adding in your functions.php, go to Events > Bookings > Recent Bookings or by clicking an specific
 * click on the Gear icon and drag&drop field "Event ID"
 */

function my_em_bookings_table_cols_template_attendee2($template, $EM_Bookings_Table){
	$template['event_id'] = 'Event ID';
	return $template;
}
add_action('em_bookings_table_cols_template', 'my_em_bookings_table_cols_template_attendee2',10,2);

function my_em_custom_booking_form_cols_attendee_list($val, $col, $EM_Booking, $EM_Bookings_Table, $csv){

	if( $col == 'event_id' ){
		$val = $EM_Booking->get_event()->event_id;
	}

	return $val;
}
add_filter('em_bookings_table_rows_col','my_em_custom_booking_form_cols_attendee_list', 10, 5);