Only dwaves can become ghosts
I normally set all useless migrants to mining and give them the suicidal Mining tasks , anyone that survives the suicide mining gets Promoted to Cannon fodder , And if they survive their Cannon fodder-ing , they get promoted to Millita , and if they survive their Fifth battle , Actual Soldier , Survive their tenth battle , Give them a proper room , Fifteen battle survived , Millita leader , Survive their 20th battle , Squad leader , Survived their twenty-fifth battle , Squad leader of a better squad , Survive a 30th battle or singlehandedly kill off a whole siege , Resignation from Millitary and a "Badass" tied to their name (Millitary Type disposition)
Or , i would Throw useless migrants into The Slave chambers and tell them to churn up as many crafts as possible with minimal food and Only Water , If anyone Survives the mini-Tantrum spiral , Remove them from the chambers and Allow them to Use the fortress's Supplies , If they get legendary , They get to work in Proper Workshops but cannot slack off for more then ten real life minutes , if they do , Another body in the Execution chamber , Once the Masterwork crafts come out of the Workshop in Massive waves , Normal citizens (Economic Type disposition)