So, them Allagans... (possible spoilers)

[zaviermhigo]

The ones who survived had a diaspora and became other people. Any Allagans who survived CT going down, ceased being allagans in a generation or two. The "descendants" in the CT storyline are clones, they were experimenting with cloning technology and that led to Xande, but before cloning Xande they tried cloning members of his family first. Remember Azys LLa is an experimentation station and a "themepark" so its not a place Allagans lived, maybe some did, but for the most part it seems like it was composed of scientists, automatons, and tourists. This is where they used the Warring Triad for yes power, but also for experimentation (sephi = huge allagans like Xande). So I think the devs are writing a pretty cohesive allagan story, Azys Lla is a cutting edge , out on the frontier research facility, not a back up for CT.

Its more like the place they experimented with things before they made it into CT. They experimented wtith capturing the warring triad before capturing bahamut.

That being said the best places for allagan lore, CT,ST, Coil, and Azys LLa in general (dungeons that come from there, one has lore inside like museum exhibits) and now the Warring Triad primals.

Graha? I think that's his name. I'm not sure he's a "descendant" per se. I think he's more or less a descendant of a family given power by the allag somehow. I could be wrong , could be mixed race, but I don't consider him a true descendant until given more proof.