How to Count on Wix Bookings Service

Probably a simple question, but I have no experience coding so any help would be appreciated.

I have set up Wix Bookings on a website.
I have created one booking sevice.
This service is a recurring class with a maximum number of 8 participants.
I have set the pricing to Varied Pricing.
There are 3 pricing options at 3 price points (single, double, triple).

Currently, the system counts each booking as +1.
This means that it is possible to book any combination of options until the count reaches 8.
For instance, 8 triple bookings can be done.

I need a way to have a counter which counts:
single bookings as +1
double bookings as +2
triple bookings as +3

Once the count reaches 8, the booking should result full and no longer allow participants to book.

Ideally (but not strictly necessary),
if the count reaches a number >=6, the triple booking option should be disabled;
if the count reaches a number >=7, the double booking option should be disabled;
if the count reaches a number =8, all booking options should be disabled.

How can I implement this solution?
Thanks in advance.