New Visa Rule about getting a letter from relatives in China??

Hi, I'm a US permanent resident that has Chinese passport, I just had my baby daughter last August and will bring her with me in October to China for 3 weeks to visit my parents. On the website (from the Chicago Consulate website, as we live in Chicago) it says that for anyone who's visiting family needs to provide a letter, so do I need to produce this letter for my baby? on the original guide it didn't say anything about a letter... Please help!