A few years ago, a user known as "The_Kusabi_" on GameFAQs discovered a sidequest in the Ultimania Final Fantasy IX guide that was buried knowledge for many, many years, especially in the West. It's as much of a curiosity as anything else, because the quest happens very late in the game, so late that the player is deep into the final dungeon before it becomes available. Not only that, the quest takes place in Lindblum, and requires the player to go back and forth from Memoria to Lindblum repeatedly to finish the quest and grab the reward. And, if that wasn't enough, doing this quest provides a fairly meager reward and will likely take you out of the running to collect Excalibur II unless you are cheating or using the speed modifier setting in the mobile and Windows versions of the game. Small wonder that the quest was buried for so long, but if you're here reading this you clearly want to know more. The quest involves Zenero and Benero's family, which are colloquially known as the "Nero" family due to the suffix all the men of the family have in their given names. Of course, the women, as you're about to see, have similar names but they end in "a." In any event, we don't really know what their real family name is, so don't go asking!
The shortest version of how to explain this quest is this: once you reach Disc 4 (mobile/Windows gamers, this means after Pandemonium), you can start returning to Lindblum to speak to Zenero and Benero at their home. Of course, you have been able to do this for a while, but now things will start to happen! To complete the quest, you need to revisit Lindblum nine times on a schedule to collect everyone. The order in which you'll find the family is:
Each visit will only give you a new Nero family member if you've completed a qualifying event first. There are far more events than necessary to complete the quest, so you needn't feel obligated to go back after every single one, but you must complete at least one of these between visits.
After you get the entire family back together, you'll get a brief scene and a chest will appear inside with your reward, a Protect Ring. Enjoy!