To add another guest
After your first product is added to the cart, you can click back on the product page to close the cart slide out or click the arrow in the upper left-hand corner of the cart slide out.
When back on the product page, make another selection and add that new selection to the cart. Keep doing this until you have all your guests accounted for.
If 1 or more guests want the same wine, then just update the quantity before adding to cart.