Here are 10 things your welcome letter or email to new members must include plus a template that can be customized for your organization. A typical NYC co-op board application will require three to six personal and professional reference letters per applicant.Below are a couple example letters and templates to point you and your references in the right direction. Trying to write a membership renewal letter but don't know where to start? We've collected some reference letters from buyers who successfully landed their desired co-ops. We've redacted contact information and any identifying details. Wondering how to write the perfect coop reference letters? You must receive a Certificate of Assumed Name from your county clerk. This certificate is often called a "business certificate."