Switzerland is a Schengen Zone country...meaning they would get in trouble there too, I believe. Easiest solution: have them leave the EU and visit Turkey so that the 90 days in the EU per 180 day time is not affected...have them make a trip out of it!


This site has everything you need to know about the Schengen Zone, and they should not exceed their visa stay, the German's actually check now, unlike they used to.
http://travel.state.gov/travel/cis_p.../cis_4361.html