We do have WP Travel Field Editor module included in WP Travel Pro which allows you to add the additional field in the Trip Enquiry form, Traveler info form, and Billing form.

WP Travel Pro plugin provides the feature of adding, editing and removing fields in Trip Enquiry form, Traveler info form, and Billing form.

You can add new field in Trip Enquiry form, Traveler info form, and Billing form by going to Admin Panel > WP Travel > Settings > Field Editor

For detail assistance regarding ‘WP Travel Field Editor’ addon, please refer link of our official documentation.

If you have any confusion then please post them in our official support forum.