If you free another team member in your group you can select them before opening the dungeon door.
I also somehoe don't get it there is an x under the other team members if you want to select more than one
I forgot that next difficulty level must be unlocked to increase team size. ( 1 > 2 > 3 )
This is far too messy right now. I need to make it more readable. I think about allowing 2x members team on the free version and extend to 3x members for version premium.