Coastal Escape Collection — 4 Gallons

Choose any combination of four gallons: shampoo, conditioner, body wash/liquid soap, and body lotion. After checkout, we will contact you to confirm your mix.

Then the customer buys the 4-gallon set, and you manually confirm the mix by email.

Later, you can add a Shopify bundle app or product options app so they can select the exact quantities on the product page.

So yes: create individual gallon products separately, but for the named collections, create them as bundle products with a note that says you’ll confirm the mix after purchase.