Hello David,

Thanks for reaching out to us. Sorry to disappoint you, but, Amelia doesn't have the conditional custom fields, yet. This is planned for future updates, but, we don't have an ETA at this moment.

The Custom Fields feature gives you the option to add more fields to your booking form so as to customize it to best match your business needs. The customer’s first and last name, email address, and phone number are there by default, but with the Custom Fields feature you can add extra fields if you want to ask a customer a question, collect additional personal details, or for any other reason.
For appointments, these fields will appear on the Booking form under the default fields, and once your customer fills them this information will be shown in the appointment information on the back-end.

Please feel free to vote for this feature on this link, as more people vote, the feature will move higher on the priority list.

You can certainly follow our changeLog page if you'd like, where we state any changes/new features/bug fixes during updates and our newsletter, so you're informed about new features, bug fixes, freebies, etc.

If you have any additional questions, feel free to ask.