The title characters are descended from Io, which gives them a claim on the king of Argos.
A recent version of this work by Charles Mee is entitled Big Love, though it isn't about polygamy per se. One character in this work tells the story of a child named Epaphus, who was the grandfather of Belus, who was himself the grandfather of the title characters. Those characters ask Pelasgus to assist them, which he does by turning away a messenger who comes to claim them. The title characters are descended from Io, which gives them a claim on the king of Argos. FTP, name this drama about an Egyptian named Danaus and his fifty daughters who don't want to get married, a work by Aeschylus.
A recent version of this work by Charles Mee is entitled Big Love, though it isn't about polygamy per se.
The {Suppliant Women} or The {Suppliants} or {Hiketides}