Multiple ICAL feed urls

Hi all,

I searched a solution to have different urls for specific categories. The only way I know is to change the core file /plugins/events-manager/em-ical.php and add more of these blocks:

if ( preg_match('/events.ics$/', $_SERVER['REQUEST_URI']) || $_SERVER['REQUEST_URI'] == '/?ical=1' ) {
	header('Content-type: text/calendar; charset=utf-8');
	header('Content-Disposition: inline; filename="events.ics"');
	//send headers
	em_locate_template('templates/ical.php', true);
	die();
}

I changed the filename to xy_events.ics and templates/ical.php to templates/xy_ical.php

I use tempate files and copied the /events-manager/templates/ical.php file and renamed it like above. In each of these files I changed the following line:

$args = array_merge(array('limit'=>$page_limit, 'page'=>'1', 'owner'=>false, 'orderby'=>'event_start_date', 'scope' => get_option('dbem_ical_scope') ), $args);

and added
'category'=>'[ID of the category e.g 42]'

The only problem is that I have to edit the em-ical.php file after every update. Is there any other way to do this?

Thanks!

Events Manager Version 5.6.2 (free)

https://wordpress.org/plugins/events-manager/