The rest of the series, on a product page

On the product page for one book in a series, show the other books in that series in reading order.

The list

In the app this list is called In this series.

What it says

Take every Book. Per entry, through the shared Series field: for each book, keep the other books that point at the same series. Sort by Series order.

On the storefront

The app writes one JSON map on the shop, lists.in-this-series, keyed by book handle with up to 20 handles each. A product page has to know which book it is: Four Mile Books stores a product metafield, custom.book, that references the Book entry, and the snippet looks the map up with that handle. The theme then loads each sibling with metaobjects.book[handle].

In your store

Other colours of this product, the other episodes of a course, the rest of a collection of prints, related articles that share a topic. Any single-reference field that groups entries into families gives you a siblings list.