Don't say anything about the original reason.
Do I then add a "Not Applicable" on the box where the question asks for original reason why she came here?
I really appreciate the answer but are you sure that I should not mention the original reason???
Do I just write a letter about the reason why I want the extension or just a small letter stating that my spouse is applying for her residency via "OutLand"

This new info about "not" saying anything about the original reason make me a bit nervous. Won't they deny the extension for not adding the original reason???