If a customer's booking was auto-confirmed, they will be given the option to edit their booking through a link in the confirmation or reminder email they receive and will be able to change the time of their booking to another auto-confirmable time slot if there is one available. The customer will see the below screen after clicking into the link:
You can restrict which bookings can be changed in this way, dependant on group size.
To set this up go to Settings:
> Select Venue
> Booking Types
> Select relevant Booking Type
> Scroll to the button to find ‘Customer Booking Changes’
> Enter the Max group size for customer changes i.e. 4.