fake bokah is so....fake. Why not just shoot it with bokah...total time saver!
Yeah, you can't do this at all and have it look realistic. They are side by side and would logically be equally blurry or sharp.
This might be just me, but in Jaszek's photo above, the blurred kid looks like he's 12 feet tall because the fake bokeh seems to be pushing him deeper into the frame.