A neat tip sent in by PCA Northeast Region that protects a portion of the registration form with a password. It doesn't hide the options from the attendee but prevents them from selecting the options without a matching password.
Create an event question with a validation rule to require a particular answer or else stop the registration.
Begin with the form builder and create an event question that collects a text answer. Give it a name like "Password", "Registrar Approval Code" or similar.
Drag it onto the form layout in an appropriate place. Remember that validation rules will be evaluated if the parent is selected. So if you place this on the root of your registration form, it will protect the entire form. If you nest it under another item, it will only be evaluated if the parent is selected/answered/etc, effectively protecting only that set of elements on the form.
Add a validation rule to the event question of type "Value is in list" and enter the password you wish to use as the value to match. Add an action where if false, SHOW ERROR and enter an error message indicating the password did not match.
Save it and your form is now partially protected!
