Hello Cathy. It's nice to hear from you. Here is what I have regarding descendents of the Retzlaff family of New York.
My Great Grandmother's name was Mathilde Johanne Ernestine Retzlaff, born January 26, 1879 in Wolcottsville, NY. She married Gustav Landow on January 12, 1899 in Wolcottsville, NY. She died about 1921.
Her daughter's names were Florence Eliza Mathilda Landow Helen Landow Mabel Landow Kenneth Landow.
Florence is my Grandmother.
From what I have seen on old certificates, Gustav must of had a brother named John and a brother Albert. There was an Albert, Jr., appearing on a certificate. These documents are all written in German, and are Luthern. There seems to be a connection to John Retzlaff' III posting as well. I will post this for his benefit, as I do not have his e-mail.