Don't forget to sell all the vendors a bag and put all their items in it before killing them.

That only works since 7.0 (and may soon be fixed).

P.s.: Oh and also dont kill, just enable the passive for non-lethal attacks and knock them unconsious. With melee attacks only; ranged and magic attacks always kill.

7.0 meaning Patch 7? That's definitely not true. I've been doing it for quite a while, and I just installed patch 7.

yes who ever told you that is wrong

my current patch 7 game i gave her the chast for rewards went down to the vendor grabbed the special loot, putting everything else in a bag then went back up the latter and killed everyone to take the chest back

Larian made a bug that can then cause this chest to disappear if you just send it to camp but that was two patches back and has its own workarounds

be sure to grab the key for the underdark and special iron before moving on after killing them