You should check out the Ley 52 or Ley de Memoria. If when your grandfather was born your great grandfather was still a spanish citizen then that might make him spanish as well and might make your father spanish as well. You should check with the Spanish Consulate in Miami and make an appointment. The law end on December 27, 2011.
The other way is if your grandfather or grandmother is spanish then you can move to spain, “empadronarte” in the city you want to live and live there for a year and that makes you eligible for Spanish citizenship, again maybe you need to see the Spanish Consulate in Miami fast.
Good luck…rbr1
