Something else: I think you'll have trouble with your generational fortress, because of the problem to generate future generations.
- On embark, you can get any gender combination, I think (I've had 1+6 once).
- A fair number of dorfs are not sexually geared for child production (homo or asexual; bi will work if the partner is of the opposite sex, though).
- In addition to that, I think some are uninteresting in a family, even if the marry.
- Dorfs only marry those within a 10 year age span (+/- 10 years), which is quite narrow for embarkers that can span over 100 years (or more) of ages.
- I think DF employs the Roman ethics on how close a relative you can marry, in which case it has to be further away than cousins. This means two couples can give you 2 locally produced generations before reaching a state where no available partners exist.
- Dorfs also have to like each other, strangely enough (mine are horrendously bad at making friends).
Given the above, you'd need 3 couples to get a fortress going long term (I think they've come up with a figure of 150 or so humans for long term viability), and that would probably be very hard to get without modifying some parameters (such as ability to select who to take on embark from a reasonably large pool, abolishing non hetero sexual alignment, relaxing age restrictions, and probably a few things on top of that).