Hi Justin!
Thanks for getting in touch with us! Let me help you with this topic.
Unfortunately, there is no built-in way to achieve what you are looking for. It might be possible by making some sort of customization, but would involve custom coding.
I don’t think it would be so easy though, as the attendee information is entered for each attendee, so you would have to apply some logic to decide which of them should you get the information from to auto-populate the billing details.
As a reference, let me point you to our themer’s guide that explains how you can customize our plugins > https://theeventscalendar.com/knowledgebase/themers-guide/
Let me know if you have any follow up questions and I’d be happy to help.
Best,
Victor