What if the heir becomes a young adult, but the previous generation hasn't finished their objectives? That happened for me in a few of the generations. Granted this was back in the era when the teen years were shorter. On the other hand, Rose can't even finish their last objective until they're an elder.
If that happens, do you allow the next generation to keep living with their parent(s) until the parent is finished with their goals?
Do you move the next generation out and ignore them while you focus on finishing their parent's goals?
Also, one of the rules for Yellow generation is that Mint is their only active caregiver until Mint dies. I know technically the rule says "only good friend", but the game mechanics pretty much guarantee that active caregivers will develop a close friendship with young children they take care of. So, although you can have Rose move out on their own temporarily before they have a child, Mint has to move in with Rose once the child is born, if not sooner.