What needs to be relinked and corrected, and in which files, for a complete creature ID replacement?
Specifically:
I am swapping the Yeti and the Goblin (regular), because the "Mercenaries" skill (Goblin help) is linked specifically to the regular goblin's ID (and upgrades if they exist); if there are no upgrades, it works only for the Goblin.
The goal: Since "Mercenaries" is a neutral unit, I need to remove the original goblin from the Orc castle by completely replacing it with another free creature.
At the moment, I have made relinks within the creatures themselves (where their stats and other data are) and similarly replaced them in the Draplins (town buildings).
Outside of town, everything seems fine, and since all upgrades are available to me, I believe I set the ID correctly. However, if I enter the recruitment screen in town, the game crashes.

Basically, the question is — what did I forget and where?!
*and for accuracy, if anyone knows, please specify the correct original name of the Yeti, something like "CREATURE_???"