the way to do it is to build a model of the complete section or city or whatever of multiple brf models in an editor likie wings, then export it and save as one brf - requiring that you reskin everything you built to draw from one .dds file.
somewhere in the ancient annals of the threads a year or so ago this was addressed, as well as errors with too many models in a scene, and load up times for a large poly scene. large polys didn't crash the scene, but high poly draws slowed loadup and movement on lower end graphics cards. still happens in a couple of the town and castle sieges - there's just too many things to draw.
my advice/recommendation then was to simulate a large town or city by having a multitude of scenes that connect when you go to a gate or whatever, so that you enetr the next section of town as if it was a doorway... like going from town center to the docks to the slums to the merchant quarter to the castle, etc.... advantage to this would be fast load times, ability to tag certain common scenes for multiple citys, as well as allowing for the implementation of random events ie muggings, beggers offering information, people needing help, whatever... kinda like what was done in the Shattenlander mod, or whatever it was called.
in any case, those are a couple of ideas on handling it. maw