1) Complete only the upper half of the affidavit. This affidavit will be linked to the original birth certificate thus becoming part of the birth record.1. Obtain the application form for amendment. The first step to updating the legal name and gender marker on your Florida Birth Certificate is to fill out the amendment form below. Complete the green form Application for Amended Birth Certificate, DH Form 429. The first step to updating the legal name on your Florida Birth Certificate is to fill out the amendment form below. This page contains all of the forms, applications and brochures available from the Bureau of Vital Statistics. This form should be used when an adult wants the court to change his or her name. Website:Amending a Record. Fill out the required form: Fill out the "Amended Birth Certificate" form, which is available on the Florida Department of Health website.