This is a question that I have been wondering about for quite a while: How did the Northern Water Tribe, while Aang instead of Korra was still the Avatar, have a chief and his royal family after Chief Arnook died later on (unseen)?
We know that Princess Yue, Chief Arnook's only child, "died" and became the next Moon Spirit, and we never saw his wife, so it's assumed his wife had already died sometime during Yue's childhood. Also, whether or not Yue's fiance, Hahn, survived both the fall from Zhao and the arctic water's temperature if he hadn't died from the fall, and we just didn't see him again in the show since he was a minor character, he no longer was going to become first the prince and then the chief due to not being engaged to Yue anymore because of her "death".
So what happened to the Northern Water Tribe in terms of rulers? Did Chief Arnook marry another woman and have another child, so that this kid would eventually grow up to become the chief or royal wife? Or did Chief Arnook appoint a high-status male waterbender or warrior as the next chief and start teaching him how to be a good ruler of his tribe before he died? Could Yue, as the Moon Spirit, have told her "former" father who the correct next leader was, and because of being a spirit, he trusted her "nomination"?
How could the Northern Water Tribe decide who the next chief and royal family was going to be with only Arnook, and no betrothed daughter having Hahn eventually become the next chief or no wife to have another child?