In certain myths, her sibling by Hades and Persephone is Zagreus. However, in the other versions it is said that Zeus *Why am I not surprised* raped her, conceiving Zagreus, who tricked Persephone into producing Melinoe. But the certain version with Zeus is less common because, since he fathered Persephone, most people find that disturbing. So, people write about that myth version much less. Either way though, Zagreus tricked Persephone into have his sister, whether it's with Hades or Zeus. Which is why this myth is, overall, passed by because of what modern society is comfortable with.
I have also read about her being directly connected to the twins (Hypnos and Thanatos) because of where she lies in ancient Greek religion. Thus, she lives in the underworld because of origins. Her name is also Latin for Dark Thought. And, Melinoe is commonly confused with Hecate, whom she is also well socialized with. A hymn *which I like* Is this I call upon Melinoe, saffron-cloaked nymph of the earth, To whom august Persephone gave birth by the mouth of the Kokytos, Upon the sacred bed of Kronian Zeus He lied to Plouton and through treachery mated with Persephone, Whose skin when she was pregnant he mangled in anger. She drives mortals to madness with her airy phantoms, As she appears in weird shapes and forms, Now plain to the eye, now shadowy, now shining in the darkness, And all this in hostile encounters in the gloom of night. But, goddess and queen of those below, I beseech you, To banish the soul's frenzy to the ends of the earth, and show a kindly and holy face to the initiates.
MelinoŽ has characteristics that seem similar to Hecate and the Erinyes as well.(But not stated in the text I read) Her limbs were black one one side of her body and white on the other, revealing her dual chthonian and heavenly aspects.The word meilia, which forms the first part of her name, was often used to describe propitiatory offerings made to the ghosts of the dead. Melinoe was probably an Orphic title for the goddess Hekate, who was sometimes named as a daughter of Zeus and Persephone.