Need help with table structure

New to the forum but have been using FMP for years. Please advise if this posting should be located elsewhere in the forum. Thanks in advance for any help offered.

I am building a DB to process registrations (200 records) for an event with activities over 4 days.

I need some help with how to design the necessary tables to make it do what it needs to do.

Registrants (Winners) can optionally bring one Guest and both Winner and Guest will register for one activity each from a choice of 20 events offered each of the 4 days. Each of the 20 daily activity choices needs to have its own inventory maximum.

As registrations are processed, the inventory will need to be reduced to prevent over-booking the activity. Both Winners and Guests pull from the same activity pool for a given activity on a given day.

Attached is a mockup used to demo to the client how the DB would look and operate.

Thanks again for any help you can provide on determining the table structure.