Hi @AntonioDB,
The best practice (from Apple) when combining Navigation and TabBar containers in the same user interface is to use the TabBar as the root container and to use a Navigation in each Tab if needed (ref: https://developer.apple.com/library/archive/documentation/WindowsViews/Conceptual/ViewControllerCatalog/Chapters/CombiningViewControllers.html ).

With the next release (should be released within the next few days) it will be possible to customize the TabBar item of a Navigation by adding a tabBarItem object to the Navigation.