Use the following trick to add other members to your family, after you already have eight members. Enable the move_objects on code. If you have a family that consists of eight members and you want to add another, delete six of your family members. Those members are not gone forever. If you want another kid, keep the parents active and try to get a baby. If you want another pet, keep one adult active and buy a pet. You will not be able to control what this new member does.