B2 Visa Sponsor Mother-In-Law, proof of relationship?

[iconwin]

Dear all members,
I am having a question and hope someone can help me out: Do I need to proof my relationship with my Mother-In-Law for B2 Visa Sponsor? If so what documents required and where/when I need to submit these proofs? I am permanent resident with greencard, my wife is also has greencard. does it matter who sponsor my mother-in-law? because my annual income is more than hers.

Thank you so much!

[immihelp]

You can show your marriage certificate to prove your wife is and she can show her birth certificate to show who her mother is.

No, it does not matter who sponsors.