Thank you again, even if that is fairly horrible news. Testing invaders will have to be done the hard way, countless hours of play and player feedback.
I am working on a simulated siege script, but it is on the back burner until I finish my thesis (as is everything else in my life). For now I have the spawning component worked out, you specify the number or a range of numbers of units to spawn, it then uses the castes pop ratios to pick the correct mix of units, it then allocates a number of skill points (user defined) to each unit, and it uses the equipment and materials available to the civilization to create appropriate uniforms. You can also overwrite all the automatic selection stuff by saying you want X of caste 1, Y of caste 2, Z of caste 3, etc... and you want a specific uniform and skill distribution. But I haven't gotten it to register as an actually siege, so it doesn't do much and the units just hang out on the edge of the map.
And of course this all bypasses the whole "army" thing DF uses now. It's possible I will try to link it to armies in the future, but again, until June all I can do is read the forums and add to my to-do list.