I really don’t think it’s a huge balance issue to let you specify your first 3 brethren. They are, after all, only 3 people, out of the 12 you will be fielding.
Also, if you’re using This War of Mine as an example, the players that want to start with two old teachers for the challenge can choose to do so, and the ones that want to start with a scavenger, a trader, and a cook for easytimes have that option as well.
