Modifying amenity

[Alabera]

Hey, I have a question.
I would like to change the 1 amenity/city from luxury resources to more.
I've only found this:
<Row ResourceType="RESOURCE_TRUFFLES" Name="LOC_RESOURCE_TRUFFLES_NAME" ResourceClassType="RESOURCECLASS_LUXURY" Happiness="4" Frequency="2"/>

So I can only change the number of cities that the luxury affects.

 

[gyogen2]

Closest thing I know of right now is the trait:
TRAIT_OWNED_LUXURY_EXTRA_AMENITIES