When I create a custom Oblivion worldspace that has a random Tower I can change the specific door on the outside of the Tower to be a unique one leading to a random interior by cloning the form, but the problem is getting out. The random interior has a door that leads back out to a "random" - i.e. determined on the way in - worldspace. The problem is that I can't add my new worldspace to that list as a destination without introducing incompatibility with any other mod that wants to do so. I can't assume there won't be any such mods, as I'm building two of them myself, and that's how I found the problem!
Making the Tower non-random avoids the problem, of course, but it's a lot of extra work creating a new set of interior cells.
There doesn't appear to be any OBSE function for adding a destination to the list dynamically, any ideas for alternatives?