...That's not how biology works. The actual criteria of being two separate species, I believe, is that the two cannot produce a fertile child between them. A horse and a donkey can breed, but a mule's always infertile, so horses and donkeys are different species. A poodle can breed with a Great Dane, so they're different races/breeds of the same species. That's the defining difference between different races and different species.
I think that they probably wouldn't accept any supervision but their own if those two wanted to see Tia.