Should your appointments be for groups of people, the client can specify the amount of persons they’d like to book for. The group booking will be displayed in admin area as one appointment.
Each of your services can have a separate capacity value, which means the minimum and the maximum number of customers allowed to book the same service for the certain time period. Each staff member can also have individual capacity settings different from the default values set in Services.
Important: This plugin is an add-on that requires the Bookly PRO installed and activated
More here: https://codecanyon.net/item/bookly-group-booking-addon/21344225