@Denne, everyone has said everything, pretty much. Cic asked for the same from me in January of this year and the few things that I sent that made a difference, from what I could see in my notes, were notarized letters from my pastor and my neighbors, as well as our joint bank account, our life insurance policy, but most importantly a declaration from my spouse attesting to the authenticity of the relationship. If you can get any or most of these it would really help. All letters need to be notarized.
Hope all goes well.