I know who the 1st six in the prophecy are:
Jason- father is Jupiter a.k.a Zeus
Piper-mother is Aphrodite
Leo-father is Hephaestus
Percy-father is Poseidon
Hazel- father is Pluto a.k.a Hades
Frank- father is Mars a.k.a Ares
Three kids (Hazel, Percy, and Jason) are children of the "Big Three"...