Hello everyone

I'm in the process of exchanging my bigger flat with someone else's smaller flat here in Geneva. As flats in Geneva can be a bit of a nightmare to find, we can't figure out which way to go:

1) the legal way - write to our regies informing of this decision and risk rejection and being put on their radar
2) the subtle way - sub-letting from each other for whatever the law allows us

Do you have any experience or know anyone who has gone through this process and care you share what you know?

I'm a C permit holder and the other party is a B permit holder if that makes any difference

Many thanks for your help
Laifu