Allow my customers to add others to the meeting invite when they are booking a meeting

Allow my customers to add others to the meeting invite when they are booking a meeting and not have to wait until the meeting is booked and then adding them after. I want to do though is have the customer input those emails as they fill out the little form after choosing a time, like "name, email, additional guests to add to the meeting). Calendly definitely has this functionality. I know i can add them after the fact but that isn't what i want.