To hide an item from the list of families and subfamilies first, access it:

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In the settings, you must select "Show" but also hide from the menu

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As the publisher of the portal, the item will be displayed with an icon indicating "hidden", and will no longer be shown to the public, although it will still be accessible from any link where you have advertised it.

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This will allow you to create your own items related to a "parent" item but which in practice do not generate much "redundant" information in the structure of families and subfamilies.