Desponia is the daughter of Demeter, goddess of the harvest, and Poseidon the god of the sea; her name means "mistress" and her brother is Areion, a immortal horse.
Demeter's children were Peresephone, Desponia,Arion_(mythology), Plutus,Eubuleus, http://wiki.answers.com/w/index.php?title=Khrysothemis_(daughter_of_Demeter)&action=edit&redlink=1s, and Amphitheus_I
Yes. Desponia, Arion, Ares, Athena, Apolo, Artemis, Aphrodite, Dionysus, Hebe, Hermes, Heracles, Helen, Hephaestus, Perseus, Mnos, Zagreus, Despoine, Plutus, and Philomelus are her siblings.
AREION (or Arion) was an immortal horse born to the goddess Demeter after she was raped by Poseidon in the shape of a horse. He was first owned by the Arkadian Ogkios, then by Herakles and finally by Adrastos.
Yes. Any children of Demeter or Zeus would be her brothers and sisters, even if only half-siblings.Zagreus, Desponia, Arion, Plutus, Philomelus, Ares, Athena, Apollo, Artemis, Aphrodite, Dionysus, Hebe, Hermes, Hercales, Helen, Hephaestus, Perseus, Minos, and the Muses.