Hi Richard,
Thanks for getting in touch!
Events Calendar PRO does include a related events feature, but not directly in the cart. In other words, it shows up to three related events on the single event page automatically, choosing events that are in the same category as the event being viewed.
I’m afraid that feature is not capable of sharing events cross-site. You can import events from one site to another using our Event Aggregator service as one possible method of sharing events between your sub-sites.
If they are exploring the event in area a, could the same be displayed as a light-box, or pop-up.
This isn’t something our plugins handle right out of the box. Sorry about that!
Could a calendar show similar events within a certain radius?
Yes, our Filter Bar add-on for The Events Calendar adds filters to the calendar view and one of the filters allows visitors to narrow the calendar to events within a specific radius of a zip code.
You can see this on our demo site: http://wpshindig.com/events/month/
Enter the ip code in the “Near” field in the search bar, then click the “Show Filters” option and Distance will be one of the ways you can narrow the list of events.
Does this help answer your question? Please let me know. 🙂
Cheers!
Geoff