Best way to add fixed items to a vendor? Use existing or new shop container?

[Pyroteknics]

Looking to make a mod that adds some specific items to a vendor and looking at the best (or cleanest) way of doing it without breaking anything else.

 

In this example, I want to add some Nuka World clothing to Shelbie Chase and Nuka World weapons to Aaron Corbett to sell in Nuka Town Market. I can see 2 ways of doing it in the CK:

 

• Add items directly to the vendors existing hidden containers (DLC04VendorChestCorbett and DLC04VendorChestShelbieChase for Aaron Corbett and Shelbie Chase respectively).
• Add a new hidden container that is separate from the original that has all the new, additional items. However, how could I get the vendors to use both chests? There would need to be 2 new chests in this case for the different items.

The second option I have seen being used in a similar mod to what I want to achieve called Useful Fallon's Basement (https://www.nexusmods.com/fallout4/mods/14588) and this mod seems to have 2 chests according to the CK when loading the mod:

 

DN049_VendorChest_Fallons (the original, non mod container for Becky Fallon).

VendorDCFallons (the new container for this mod that adds specific, extra items for Becky Fallon to sell).

 

The mod above uses the 2 containers together and Becky Fallon uses both of them together in the same shop window (the mod adds a fixed amount of 10 clothing for nearly all non-DLC clothes) - I can't see how this 'linking' is done in the CK, how is this done?

 

Thanks in advance!

[Zorkaz]

One of my ways

1. Create a marker (Maybe movable static, persistent)

2. Attach a script on the Marker, OnCellLoad(), that adds the item to the original vendor chest, maybe to the vendor NPC as well.

 

 

OnCellLoad() doesnt' trigger at first, when loading a safe in the respective cell but will so after you walk around