i-864 question

[invasian 2]

Hello I am petitioning for my parents to come. I am at the stage of Nvc and have questions for the i-864.

 

I currently do not make enough income to support the both of my parents so i plan to use my spouses income since she makes more than myself along with i-864a for her. We both file taxes jointly

 

Questions

1. What supporting documents do we need for my spouses i-864a and in what order do they have to be?

2. Do we need marriage certificates to prove that we are married?

3. Since we file taxes together do i still need to make the same tax copies for my i-864 and her i-864a?

 

Thanks any help is greatly appreciated as everything else I found answers within the boards but these are just some questions that I can't seem to understand.

 

[invasian 2]

Also do we need any evidence to support her citizenship?