When ever I see something like this I remind myself that the writing team is amazing and can do no wrong. I'm sure any new character introduced will be beloved just like the others.

That being said:

First: Horrifying, Second: I think the idea that EQD had about it being Shining Armor and Cadance's offspring may be right. I am curious though, as the image of her seems to show her being CMC age, even I assume she would have to be younger than the cake twins.