Very good question. It applies not just to Switzerland, but to everywhere. What happens if you die while in one country, while your will was written in another? Or if the surviving relatives are in a different country entirely. Which country would have jurisdiction in a dispute?

Surely there must be some sort of international agreement on this? What about when taxes come into play? Some countries tax inheritances...

P.S. I don't think you can do any formatting in the subject line - but thanks for trying (I tried too)