Small backpack that can be attached to a bigger one, does it exist? [closed]

I normally carry a very small backpack around but when I need my laptop or something else bigger, I grab the bigger one:

The problem is that I then need to move a lot of things from the small one to the big one or have duplicates (painkillers I can duplicate; notebook and glasses, I need to remember to move).

Is there a solution around these sizes where I can attach the smaller backpack to the bigger one?

I thought something like the Mira 2-in-1 Pack, but the problem there is that the detachable pouch is not a backpack but a sort of messenger bags.

Another alternative I thought of something like this:

http://www.eod-gear.com/warrior-assault-systems-load-bearing-molle-harness-with-rear-panel/

and use a molle pouch as small backpack and have a normal backpack with molle weaving to attach it to. But it looks way too clunky.