marriage certificate : is it mandatory ?

[05skp12]

hi
i want to get my inlaws to US. But i do not have a marriage certificate . is marriage certificate mandatory to get them here ?

pls let me knwo
thanks

[immihelp]

If you are sponsoring them, you have to prove that they are in-laws. Marriage certificate proves that.

If your spouse is sponsoring them, he/she has to prove that he/she is their son/daughter.