Adding Sellable Items To Merchant NPC

First you set the NPC's AI-Settings to buy/sell what you intend to. (An Alchemist isn't very likely to buy or sell armor...) You can also simply choose one of the predefined merchant-classes.

Once you've set this, the NPC will sell everything he owns and hasn't equipped yet.

- Objects from his inventory

- Objects from a container he owns

- Objects from a cell he owns, that don't belong to someone else

- Objects from containers in a cell he owns, that don't belong to someone else

(To set up cell-ownership go to the right-click on the cell in the "cell"-window, choose Edit...Interior Data)

Everything a NPC buys will either go to the "Merchant Container" you've associated in the NPC's reference-window, or to his inventory when he doesn't have a container. (Which will cause them to equip good stuff like in Morrowind)

There are two ways to prevent a npc from selling stuff (Like the family-shield on the wall of an armorer's shop):

1. Don't set the cell to be owned by the NPC, and give him explicit ownership for each object he should sell.

2. Choose another owner for the objects that the NPC doesn't want to sell.