Killer is important to the essence that is Baby K because he is the origin for The Babe's name. The K in Baby K stands for Killer.
Lemmy is perhaps most to thank/blame for the existence of Baby K Lemmy is the pep-pep to Baby K.
Butterball is important to the cutestcat family and origin because she was the original fat cat. When The Babe was just a tiny kitten Butterball was becoming a veteran in the art of being a fat orange cat.