Of course they need to stop (on their own, not in case they are stopped) and declare the stuff at the customs, giving in a completed form 18.44.
There is nothing to pay. But if they dont then they are liable of tax of 8% of the total value (EVEN if the stuff was yours and pre-owned!)
[That is not the fine - It's just the import taxes, as by not filling the form you agreed that you want to pay tax on it]
So why risk it? The do stop people if they see lots of expensive stuff in the back of the car!
You also need an inventory in English (a list of bullet points on the contents of each box, eg box1: plates and cutlery, box2: tv).
And they must cross the border together (all your goods enter into Switzerland at the same time).
See here: http://www.ezv.admin.ch/zollinfo_pri...x.html?lang=en
Under "hosehold effects moving", the form is in English at the right of the screen.