I'm pretty sure when you CreateCreature() you use the .cre file name and not the death variable.
A death variable is a unique identifier (ok, it doesn't *have* to be unique, but for a joinable
NPC it should be). It's used in scripting/dialog triggers and actions and is generally some form of the
NPC's name (although, again, it doesn't *have* to be).
If you're using Near Infinity, you'd open up your .cre file and click on the edit tab to input those variables/names.
Your .cre file will eventually need to end up in the override, but if you're planning on making a distributable mod it's better to set up a mod directory in your
BG2 main directory and have stuff copied over via the .tp2 file.