Who is Hades mother in law?

Hades' mother-in-law is Demeter, the goddess of the harvest and agriculture in Greek mythology. She is the mother of Persephone, Hades' wife, whom he abducted to the Underworld. Demeter's grief over Persephone's absence is said to cause the changing seasons. Thus, Hades is linked to Demeter through his marriage to her daughter.