I am trying to create a custom export setup and started with the walls. I noticed that walls are catagorized by the function parameter under construction. This is not working for us because many of the wall types are used for both interior and exterior. I need to create a new parameter that I can add to the walls so that I can assign CAD layers to them by subcatagories that I have created myself. I just need to know how to add an additional parameter to the wall system family. Can anyone help me do this?

Thanks in advance!