Make a display of souvenirs buyable (add new "func" tag)

Hi all!
I converted the souvenir display from sims 2 for the sims 4 i.imgur.com/HjM75K9.jpg . Now i'd like to make possible an interaction in order to buy the palm object and the pirate treasure chest object.
I imagine a window like the one used for "city living" festival stands. Within this windows will be possible to choose which object i want to buy.

I already converted the single objects (palm+pirate treasure chest). I noticed that the game stands use "category" to recall objects that will display in the "buy souvenir window". But i don't know how to create a new category tag called "beach souvenir"

Here are my findings:

1) [OBJ TUNING OF LOGIC STAND] This is the category that recalls objects. Only objects with this "func" will display in the buy window


2) [OBJ CATALOG TAG OF FIREWORKS OBJECT] This is the "func" of the fireworks objects. As you can see there is the "func_fireworkslogic". So you will find this object in the stand.


The "func" list is default, and i can not add a new one. Is it possible?

Thanks