the legal advice I received was that it doesn’t have to be notarized, but you can do it for extra credibility

if you decide not to notarize the letters please make sure that it is stated to be true and correct under penalties of perjury in the place where they are signed.

I got the same and yes you have to get them notarized

no, you don’t have to notarized letters from a person third. I asked my lawyer and she said it’s not necessary!

thanks everyone.