I went to an open house for a potential employer/friend of the family, and met somebody who I'm interested in. Unfortunately I was swept away to be shown the new master bathroom before names could be exchanged. What makes it awkward is that they may be related (cousins?) to the potential employer, and as I'm very interested in living and working full time here, I can't risk compromising my job by asking the potential employer who this was.

Any advice on how to find this person in a Swiss way? A way to ask the employer without revealing my intentions?

Merci!

Ask someone else who was at the same party? No guarantees it won't get back to your potential employer, of course, but to be honest you seem like a nice fellow - unless the lady is underage or already spoken for, I doubt her cousins would take such a dim view as all that.

1st get the job

2nd get the lady

But don't get your meat where you get your bread..

Leave a note in his mailbox?

I should imagine that making a polite enquiry would hardly be likely to lead to you compromising your future. You could approach it from a myriad of stances. Just be polite and direct. Either that or walk away and wait for chance to cross your paths once again.