You're right, that's correct. I just meant that in the sense of "the brother that has been long lost to you" because Ao Yue (going by Xuan Yue now) grew up not knowing who his parents are and that he even has an older brother, and Ao Gu is himself didn't know where his disowned brother was, for a while.
Ao Yue is Ao Gu's real brother, who was exiled and grew up not knowing his real identity as a prince, and who died and was resurrected in the form of a baby, after which his new baby self was renamed AoAo... AoAo is (and has always been) only the resurrected form of Ao Yue, reduced to the form of a child with no memories of his past after he (almost) died, who was taken back to his original home in the Eastern Sea and raised by Ao Gu as his little brother.

Ao Gu, pay attention, that person you just passed by is your long-lost little brother Ao Yue, who goes by "Xuan Yue" now, and who will soon die and be revived as a baby with no dragon pearl, called AoAo. Don't forget to go pick him up and take him back home, and he hates the name "AoAo" so please think of something else to christen him!.