Hi Yuval,
Thanks for getting in touch!
If I understand correctly you would like to add that extra string to the ticket URLs that point to the Eventbrite site. Is that correct?
The field on your WordPress website running TEC which contains the Eventbrite tickets is an iframe. The source comes from Eventbrite itself.
There is a possibility to modify the content with the ‘tribe_events_eventbrite_the_tickets’ filter, something like this:
add_filter( 'tribe_events_eventbrite_the_tickets', 'myfun' );
function myfun ( $orig ) {
// Do whatever to $orig
return $orig;
}
You can try to do a pattern match and then replace or something similar to add the desired string to the urls.
I hope this will help you get started. Let me know.
Cheers,
Andras