There are one or more virtual or base catalogs containing product and category
definitions.
At the Content Editor:
CAUTION:
Re-index the site immediately after changing catalogs. If the site
is using an old index, new content will not appear and deactivated content will
persist.
Browse to the category to edit under: /sitecore/Commerce/Catalog
Management/Catalogs/
Select the product in the content tree.
Expand the Commerce Hierarchy in the content area
Use the Child Products add them within the content tree
hierarchy.
You can double click a category to toggle it between the
Selected box.
Save your changes.
Click Save on the Home
ribbon.
Catalog Items are available in the content tree. If required, you can
refresh the Catalogs node by collapsing it, then expanding it
again.