Upvio allows you to specify which services your customer can add additional guests for.
To enable guest invitations for a service, you will go to services and click on the specific service. You will then go to the guest tab and enable the "Enable guests" toggle.
When the booking page is accessed, all the normal steps will be required, but the last step will request your customer to add in additional guest information before confirming the appointment. They will be able to add a maximum of 25 guests.
All guests will also receive a calendar invitation to the appointment. If you do not want customer data completed in the booking process to be displayed in the calendar invites, it is extremely important to ensure that "Include customer data" is disabled in the Calendar connections screen as displayed below.