One thing I cannot work out is how to shrink an object so that the smaller one "recedes" equally from all borders of the original object. A picture might help:

You can see how the smaller version ("shrunk" using CTRL-SHIFT-drag-corner) will no longer overlap the larger blue original.
What I want is for the smaller image to be a "thinner" version of the original, overlapping it entirely.
There is probably a simple way to do this, but despite searching the forums, reading the manuals, and doing a bit of googling, I cannot figure it out! All help appreciated!