Hi Betty,

Here are a couple of Florida death records for a Michael Willis. You could request the obituary from the library and see if it gives the names of his siblings. The first one looks close to your dad's age..........worth a try.

Name: Michael Clay Willis
Death Date: 6 Oct 1992
County of Death: Monroe
State of Death: Florida
Age at Death: 47
Race: White
Gender: Unknown
Birth Date: 29 Jun 1945

Name: Michael David Willis
Death Date: 18 Oct 1996
County of Death: Dade
State of Death: Florida
Age at Death: 44
Race: White
Gender: Unknown
Birth Date: 15 Jan 1952

Kind regards
Darlene
BC Canada