Do you think those girls are going too far with this in plastic surgery?

yes, that is way too far

Define going too far. Seriously. It changes with each generation, and from culture to culture. I dislike most body modifications.. I think peircings and tattoos are cool, but I dislike the "out there" things like gauging the ear lobes. But I what I think is going too far, was a symbol of nobility and community respect in past societies. Same thing with this. Yeah, I think a third breast is weird. But, I bet somewhere are people who like it, and will find these people more attractive for it.

Consequently, I had not heard about that specific kind of modification, though I also dont usually keep up with all that stuff

Any plastic surgery is too far.

never heard of it. Sounds like a horror movie. so yeah I do think it is too far.

If that's what they want, they should be able to get it.