If you need to collect more than Yes or No responses, like Maybe or a specific Date and Time, we recommend using custom form questions to collect that information.
Under Setup > Registration, please confirm that the "Allow Guests to RSVP No / Not Attending" box is unchecked. By doing that, all potential attendees will be funneled to the RSVP form to complete it.
Then, with a premium plan, you can add custom questions to your registration form. We often have people set it up this way:
Question: Can you attend?
Multiple Choice: Yes, No, Maybe
Question: If you can attend, which time is best?
Multiple Choice: 9:00am, 10:00am, 11:00am
You can see these responses in your Attendee List or Attendees Report to sort responses or send appropriate information.