The family name Mergen is in Luxemburg like Jones or Smith is in the US or UK. Or Schmidt is in Germany. But there are only about 300.000 inhabitants, so the actual number of Mergen's is relatively low. And lots of Lux. people moved "into the world". In the Elzas (France) just south of Luxemburg, there is supposed to be a Mergenthal (M valley). Although it could be that this valley is names after a Mergen, it could also be the other way around.I myself am having still the Luxemburg nationality, although I'm born and raised in The Netherlands. But visiting Luxemburg every year.