How to prove 401k and insurance beneficiary

[somanesh]

I'm in the process of filing i-130 for myself through my spouse.
As part of bonafide marriage supporting docs, I'm adding the beneficary info from my 401k and insurance. Is it sufficient to take screenshots of beneficiary information from the 401k and insurance portal page? Or is it required to have an official letter from the 401k and insurance department stating my spouse is my beneficiary?

Thanks in advance