Modding

While working on the mod, or more specifically, while creating an alternative creature branch, I encountered a problem: one of the creatures doesn't appear in the hiring window. The creature was supposed to replace the Knight, but it didn't happen (although the Dire Wolf easily took the place of the Zealot). At the same time, the Knight can still be upgraded into the creature that doesn't appear in the hiring window. Could there be some parameter other than BaseCreature that controls this?

UPD: The creature shares a slot with the Dire Wolves. How can I split it into two slots?