Hi Gary,
Thanks so much for reaching out!
One way to be able to achieve this would be to set up a different e-commerce solution for your tickets only. With Easy Digital Downloads, you cannot sell merchandise additionally, so this would prevent users from doing both. You can read more about Easy Digital Downloads vs WooCommerce here:
https://theeventscalendar.com/knowledgebase/choosing-ecommerce/
You may be able to make something like this work with a customization as well, although we are limited by our Support Policy in how much we can help with customizations.
If this functionality is a requirement for your intended project, I’d suggest that a third-party developer would be the best way to make this feature happen on a short timeline. ? We maintain a list of developers who work with our plugins on our Knowledgebase here:
https://theeventscalendar.com/knowledgebase/find-a-customizer/
Let me know how it goes!
Thanks,
Jaime