Keeping that Hypnos is the son of Nyx - his sisters would be the death goddess Ker, Oizys the goddess of misery, the Hesperides, the Keres - death spirits - the fateful Moirai, Nemesis goddess of retribution, Apatê of deceit, and Philotês of friendship/sex, and Eris of strife.
The Greek god Poseidon was sisters with Hera, Hestia, and Demeter.
His brothers and sisters.
Hestia was the oldest child of her brothers and sisters
Leto had only one sister; Asteria.
The Greek God ares is know as the God of war. he usually wears a helmet and a shield. He has a brother called Hephaestus, and sisters named Eileithyia and Hebe. he is the son of Zeus and Hera.
"Sisters" in English is αδελφές (adelfes) in Greek.
Apollo, greek goddess of the sun, had one sister, whose name was Artemis, goddess of the moon and the Hunt.
Any son or daughter of Hermes would be thought a half-sibling of Pan.
Any son or daughter of Hermes would be thought a half-sibling of Pan.
Athena, the Greek god of wisdom, is related to the other gods. such as Zeus, hades, Poseidon etc.
I believe Athena Aphrodite Apollo Artemis hestia hepheasus ares ( I think that's it )
Hypnos, the god of sleep, is the father of Morpheus, and chief of 1000 Dream gods, so yes - he may have had brothers and sisters too.