I've got a similar case. They nipped over to Fontainebleau around 1872 and were there at least long enough for a son to be born. They were in service, so I'm guessing the family they worked for were in France, but I don't know. I'm just now going painstakingly through the census records....which aren't alphabetical If you know where in France they were, AND if that Department and Commune has digitised their records, you could look through the census -- they're every five years, more or less, and usually quite easy to read (if you need a hand translating the column headings, just shout out). The tricky bit is knowing what area to look in.
Lots of fun!