Sub Collections

In product setting:

Result:

Choosing the metafield (version 1.3.0)

The Sub collection section reads this content through its Subcollection metafield setting. The default key is custom.subcollection.

Keep the default key above and it works with no extra setup.
Or rename it: create the metafield under your own namespace.key (for example, your brand name), then set Subcollection metafield to match.
Reuse on one page: create one metafield per copy (for example custom.subcollection and custom.subcollection_2) and point each Subcollection metafield at its own key to show different content.