I’m not at my work pc right now so I can’t take any pics for you, but I did something similar in my project. Basically, I added a boolean variable to units that marked them as a spawner entity, and modified the grid manager function that adds pawns to the pawn array to ignore those units effectively hiding them from the game. It’s been a while since I played disgaea, so I don’t remember exactly how it works, but iirc you click your spawner and you get a menu of your units, and you can pick one to spawn.
If that’s what you want to do, you could pull it off by doing what I did, and then creating an array for your spawner(s) within the grid manager, and having it add your spawner to that array at startup (like it does with pawns). Then add the functionality within the player controller to call a menu that lists your available units when you click the spawner, then when you select one add it to the pawn array at the spawner location.