I haven't got really deep into how the door activation system works in Nif-files. My current dilemma is about how to make a static object into a door. What I mean is that I don't want to replace the original object but I want to place an invisible object near that static object that will also function as a door. I've tried the method of making the texture's alpha channel for the door object completely black. Now the door is see-through but it still can be seen from different angles. So what I'm looking for is kind of a collision box that will also function as door when you activate it, but it's still invisible. Is there a sensible method for doing this?