It wouldn't be necessary to draw it at all, it would be possible to just mention that there is such a possibility and leave this generation in the world as "lore" or simply "knowledge" and that's it.

Theoretically, this would add the possibility of even creating that kind of character with such a legacy (e.g. if the creator wanted to make a sequel someday or even in future quests).

Additionally, another argument is that CB is generally already closer to either a human or a beast, so if a human and a beast can have offspring, then CB and human/beast even more. And don't cite here the example of an animal such as a mule, it was a deliberately created hybrid and even in their cases there are fertile individuals.

P.S. It's better to introduce any changes and support them now when the game is still in early version 0.28 than when it develops or is nearing completion. If it Really REALLY doesn't suit the author "plot-wise" then you can simply say that it's difficult and that the few offspring are either human or beast and that's it.