I'm on the chapter where you recruit Geitz, but I forgot I need Dart to recruit him. I didn't choose him when I chose my units and I can't find any option in game to restart the chapter. I would have just went back to a save state before the battle but, unfortunately I saved when the battle already started, so if I went back to that state I still wouldn't be able to add Dart to my army. There probably is an option to restart but I'm just too dumb to find it.