I am a law school graduate. What I offer is mere information, not to be construed as forming an attorney client relationship.
Get an attorney ASAP in FLORIDA who has experience with wrongful death and possible survival statutes laws.
Wrongful death == you are suing on behalf of the family for his wrongful death and associated expenses like funeral, etc.
Survival statutes == you are suing on behalf of your brother, the wife and unborn baby for any possible pain and suffering they felt before they died, as a result of this accident. I.e. autopsy will help here, forensics reports, police reports.