not always just 3, there are several types and kinds. some types don't even use same species as another type might have in them. what 3 species, i dunno. i do know is that for ZZ types a trimac is used. kamfas i think use syspilum, or other vieja species. not sure exactly where the pearls come from, possibly texas cichlid types, or JD's, maybe red terrors, jags, i dunno, pure speculation on my part.
i do think that FH's are line bred, and simply crossing 3 types of cichlids will not produce a great FH. might get something cool for your own tanks, but not something great that FH fanatics will spend alot of money for.