Isn't there a new study that suggest that the people of Pompeii died from a pyroclastic flow (something about most of the bodies being in roughly the same layer of pumice)
And the people at the boat shed died from thermal shock
Personally, I don't think that the concept of belonging is explored thoroughly enough in the Inheritance series. Also I don't think that it is a major part of the books. Use it if you want, It's up to you.
Try this for seggestions or related material...