You could separate and complicate it even more:
- Use a DEAD civ and have you ~17 dorfs (7 + 2 waves) set up a rudimentary surface facility for visitors, and connect this one with the "real" one underground populated by dorfs with a fully automatic mine cart route (to send stuff up [and, eventually, down]).
- Isolate the dorfs in the lower facility with a sealed airlock in between the surface and the subsurface, and place a lever in the airlock.
- Designate tavern, library, and temple in the surface facility (as well as in the subsurface one).
- When keep an eye out for visitors who want to have a meeting, and send the expedition leader to a burrow in the airlock by order the lever to be pulled on repeat (the lever should be profiled to be usable only by the expedition leader). Seal the "lower" drawbridge behind the expedition leader, and open the "upper" one to let petitioners through. Accept/reject petitions as you see fit, and let the surfacers live in the topside facilities (you need to send up food and booze, and optionally clothing). When the petitioners have left, reseal the "upper" drawbridge and open the "lower" one, releasing the expedition leader from the burrow.
- Eventually you should get citizenship petitions, and when you accept those you then finally get a workforce to start building stuff, growing surface crops, expand the facilities, and even build and man a trade depot, etc.
- Using the mine cart connection you can send down surface crops (and wood) for processing, and place additional beds sent up from below to expand the furniture (until you get enough citizens topside to produce things locally).
The above is a bit too much work for me, but might be of interest to those who want that kind of a challenge.