Here is a list of unseen or mentioned-only characters on One Day at a Time.
Alvarez Family Members
Maruchi is one of Lydia's younger sisters. When Lydia debuted as a Dancer and she wore mother's heels. But when she stepped on the dance floor she saw Maruchi had also entered the competition. This is a story she told her children several times because Penelope and Tito already knew about it.
Berkowitz Family Members
Sophie Berkowitz was the ex-wife of Leslie Berkowitz and the mother of Katie and Rachel. They got divorced after she slept with his podiatrist. She would yell at him saying she hated him, and they had a messy divorce. In "Hermanos," he says he has night terrors about Sophie strangling him. We learn her name in "Perfect."
Katie and Rachel Berkowitz
Katie and Rachel Berkowitz are the daughters of Leslie and Sophie Berkowitz. They are in their thirties and they do not have a good relationship with their father and only use him for money. He was sent the bill for their houses and weddings even though he was never there to see them.
In "No Mass," Leslie is talking on the phone with Katie and fought over her being unemployed and he being worried that her "self-published vampire erotica" won't be successful. In "She Drives Me Crazy," Elena tries to improve his relationship with Rachel by driving to Rachel's home, and she emptied his wallet in person, making him happy.