To hide an item of its own from the list of families and subfamilies, you must first access it:
In the settings, you must select that you want to "Show" but also hide from the menu
As the editor of the portal, the item will be seen with an icon that indicates "hidden", and for the public it will no longer be displayed, although it will still be accessible from any link where you have advertised it.
This way you can create your own items related to a "parent" item but that in practice do not generate a lot of "redundant" information in the structure of families and subfamilies.