How many kids does Demeter got?

Persephone, goddess of the grain (by Zeus)

Ploutos, god of wealth (by Iasion)

Philomelus/Bootes, invented the wagon and the plough. (by Iasion)

Korybas, leader of the Samothracian Korybantes (by Iasion)

Eubouleus, demi-god (by Karmanor)

Khrysothemis, demi-goddess (by Karmanor)

Despoine, mystery goddess (by Poseidon)

Areion, immortal horse (by Poseidon)

Demeter was sometimes titled Erinys Telphousia it may be assumed that she and not a Erinys the creatures:

Aithon, Phlogeus, Konabos and Phobos, fire-breathing, immortal horses which drew the chariot of the god Ares. (by Boreas)

Dragon of Ismenus, Cadmus slew and from sown teeth Spartoi grew (by Ares)