Okay, I think I figured it out. The seal lion unbirths the wolf, then the dog unbirths the sea lion, and while unbirthed the wolf cock-vores the sea lion and cums her out. I think. Which is stupid, clearly if they were going for -ception they should have had the dog get cock vored instead. ¯_(ツ)_/¯
So the seal acts as a protective shell for the dog? Or did the seal unbirth the dog while inside the dog girl, so the dog is expelled while the seal girl is... ? Absorbed and transformed into bigger tits and vagoo for the dog girl? (Asking for a friend.)