Review the whole structure semantic

[magicoli]

We are usually selling

• Goods (merchandising, souvenirs, food & drinks)
• Services (holiday rental, restaurant, transports, excursions...)

And booking is a feature of these sales, not a kind of prestation by itself. So the object kinds should be

• Client
• Quotes (initial state of prestations) including one or more items, quantities calculated
• Quote items, can have one or more quantity multiplicators, depending on type (quantity, guests, guests[category], dates, hours...)
• Prestations (accepted quote, linked to quote items)
• Invoices (linked to prestations, can use a third-party library)
• Booking, linked to prestations quote items
• Tax rates, linked to quote items, inclusive or exclusive, fixed or percentage, unique or multiplied quote item multiplicators, cumulative (requires priority to calculate in the right order) or mutually exclusive (per tax category)