Hi Adam,
Thanks for taking the time to reach out! If you’re willing to perform manual updates to ensure that events are synced between two sites, you can use WordPress’s built-in import/export tools to export events from one site and move them to another. You can read more about this process on our Knowledgebase here:
https://theeventscalendar.com/knowledgebase/using-wordpress-export-tools-to-migrate-events-content/
However, you’ll likely have the best experience using Event Aggregator to automatically import events from one site to another. This Knowledgebase article details the process for creating a “hub” site that groups events from multiple sites running The Events Calendar, but the same process could also be used for copying events from one site to another. I’d suggest reviewing both processes to see which one is right for you and your client!
https://theeventscalendar.com/knowledgebase/creating-hub-site-event-aggregator/
I hope that helps to get you started here! Thanks again, and let me know if you should have any other questions! 🙂