Deleted42692105User

I have two questions, I have searched the internet for various days now to no avail. First question, how do I edit DLC items in the toolset? They don't appear anywhere. Second, how do I edit header files and make them work? I've been placing them in the override directory and nothing happens. Any help is appreciated greatly.

How would this be possible? I tried looking for a record that made that change in TES5Edit but to no avail.