I had to do that like 5 times in a row for it to work! I ended up having everyone go ranged and have wyll run in melee. If you ONLY target the boss, getting him to 1 ends the entire fight and the guy talks to the nearest person - Wyll in that case. If Wyll makes the decision to kill him he says "darnit we needed him unconscious to talk to him!" lol. After killing him a few times it worked. To skip the annoyance I think letting him go might work? I didn't try it but its a buggy quest for sure.

What is the problem you are solving? Does your proposed change solve the problem? Is your change feasible? What else will be affected by your change? Will your change impact revenue? Does your change align with the goals and strategies of the organizations (Larian, WotC)?