Maybe Frank&Nancy adopt these kids. Luann gets what she wants (kids to take care of without romantic entanglements), Bernice and Piro get what they want (each other without child rearing responsibilities), Shannon gets what she wants (6 playmates to lord over) and we get 6 new characters to grow the Luannverse.
Your grandmother moved out at age 12? There’s a story I’d like to hear more of!