I am only looking at the image as posted. To magnify it significantly IMHO defeats the purpose of the exercise, and goes back to the issue of magnifying to find fault that isn't there without the magnification.

Perhaps, it OK in these types of "tests" to magnify to find the changes, is it?

Anyway, my gut suggests that the chick was added.

I keep looking at the front outline of the chick against the mom and it is too clean.

Also the line of the chick's throat against the dark brown of the mother is too clean.

I would expect that the chick would be very close to the adult; yet the line of the chick is so much sharper than the adult's feathers.

Having said this, the adult's eye does appear to be looking back and therefore could be looking at the chick or something else.

On the adult's left wing edge there is a bit of a feather sticking out, and the BG at that point on my monitor is lighter than in that general area close to that particular feather sticking out than farther away towards the adult's beak.