replace mesh on skeleton

[Sebo85]

So I'm (still) trying to get a wide vault door and I wanted to do a wider version of the DLC vault door to fit into a wide doorway.

 

Since this door actually has a skeleton to 'collapse' while opening and no simple open/close animation I just wanted to recreate the bstrishape of that dlc door but I don't know how to do it cause I can't isolate the visible mesh to open it up on Blender AND to replace it in nifskope after editing it.

 

The collision is another part which I don't know how to edit :D

 

 

Thanks for any advice