Doug and Susan
Doug and Susan were friends of Helen and Jake's, with a toddler named Ramona.
Their only appearance is a very brief one in College Bored, where the two families meet to chew the fat (much to the boredom of Daria and Quinn). He and his wife are shown as a little too anxious about their daugther's future school grades: they're reading "My First SATs" to her.
It's not clear if the Morgendorffers knew them before the recent move to Lawndale or if they're recent friends, and how they met them in either case.