There are a couple of groups of penguins standing around that we still need to add. One on the floe in front of the huge iceberg, the other gathered at the top of the iceberg itself. It looks like the light is a little more direct and brighter back there so we'll change the luminance of the penguins somewhat to hopefully get that across. It's possible to do all the penguins in one go but it would create some problems. If we have the penguins getting smaller by vertical distance, large at the bottom of the image, small at the top, then the distances are going to start looking strange as the penguins on the iceberg are going to be much much smaller than those standing a small distance in front of it ( Because they are so much higher up the image ). Doing these in a separate block gives us a bit more control.

Add another new layer above the previous one, fill it with white and lower the opacity to 50% again. Now paint in the two areas that we want to see the penguins appear, like the image below. Once this is done, raise the opacity of the layer back to 100% and launch Scatter.

As it looks a bit brighter back there, especially near the top of the iceberg so let's change the overall luminance of the penguins to try and reflect that. In the Color panel change the Luminance setting to 'Vertical distance' 45% at top, 34% at bottom.

The penguins are still rather big for how far away they are meant to be, so go to the Variants panel and change the scale setting to 13% at top, 24% at bottom.

At this point I played around with the shadow settings until it looked about right to me. Set the radius to 49%, opacity to 31%, X offset to -6% and Y offset to 16%. Apply Scatter once more and if need be move the layer up or down slightly to more precisely match the penguins to the background.