'What's the Material Design way to add elements to a sub-list?

Say you have a list of switch preferences and one of them has its own list of preferences, like so: enter image description here

As you can see there is a green FAB on the right that allows the user to save, and there is a "+" button below the sublist that allows the user to add elements to this sublist. Is this "+" button the correct way to add elements to the sublist?



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