Yes, definitely agree there should be more realistic ways to handle Mayrina’s brothers. I’m not sure that leaving them knocked out in a swamp full of goblins and redcaps is going to be much different from killing them, but if we could knock them out and then heal and talk some sense into them, or if as the OP suggests, the other brother will surrender if his brother is knocked out, that would feel more satisfying.

I know this has been discussed before, most recently maybe in https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=837100.

"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"