How do I add or change the heroes in Stationing Management?

If you have recruited a hero that can be stationed then they will appear in the management station interface with the option to station them. You will need to have the cost capacity to do this though so you may need to upgrade the building.

The hero for Iron production is called 'The Alchemist'. A purple develop hero. He is either very rare and hard to recruit or possibly limited to being unlocked via the Limited recruitment paid for option. (Benefits Center). I haven't unlocked him yet.