
Quoting
Florida Statutes, Sec. 382.013(3) - Birth registration
(3) Name of Child. --
(a) If the mother is married at the time of birth, the mother and father whose names are entered on the birth certificate shall select the given names and surname of the child if both parents have custody of the child, otherwise the parent who has custody shall select the child's name.
(b) If the mother and father whose names are entered on the birth certificate disagree on the surname of the child and both parents have custody of the child, the surname selected by the father and the surname selected by the mother shall both be entered on the birth certificate, separated by a hyphen, with the selected names entered in alphabetical order. If the parents disagree on the selection of a given name, the given name may not be entered on the certificate until a joint agreement that lists the agreed upon given name and is notarized by both parents is submitted to the department, or until a given name is selected by a court.
(c) If the mother is not married at the time of birth, the parent who will have custody of the child shall select the child's given name and surname.
(d) If multiple names of the child exceed the space provided on the face of the birth certificate they shall be listed on the back of the certificate. Names listed on the back of the certificate shall be part of the official record.