We have also added a letter from an Ontario MPP and the Mayor of the Village where I live!
I'm not sure how far this will help you. It's more about a testimony of people that know you well as a couple. If the mayor and the MPP are good friends of you and your spouse, that will work. If they do not know you at all, it won't help you.
we simply provided four letters from individuals (friends and colleagues) that knew about our relationship right from the start. small paragraph about the person, relationship to the sponsor/spouse, supporting line (that based in their best knowledge the relationship is genuine), including (company)email address and phone number.
no questions from beijing were ask and everything went smoothly...