raistlin i wouldn't worry too much about the language situation, your daughter is at an excellent age for a third language. The most important thing is to get her as much exposure to the language as possible.
You don't say how long your planning to stay. If it's for the long term and your not planning to send your daughter to a private French or English speaking school then a local play group would be a good start. These are run by a trained leader. The emphasis is on social integration but whoever is taking her can stay for as long as it needs for the child to become secure in her environment. It's also a good way for whichever parent is around to connect with locals. A lot of people do speak French in the German speaking part of Switzerland.
An important factor is that each parents sticks to their own language at home. EG. you in English, your partner in French ( just a presumption) this keeps the emotional connection of the individual languages separate and benefits the child more than chopping and changing between the two.
I would advise you not to try to teach her German at home as it's important for the inner- language mechanism to hear the new language in the right cadence. However most villages or towns have a library that rent out CD's and DVD's as a source of hearing the language at home.
I know it's hard to resist but try not to over expose her at home with German, the occasional film that she already knows in her own language could help, (watch it with her) as soon as she loses interest turn it off.
As soon as you know exactly were you'll be living the combined knowledge here at EF will probably be able to offer more specific assistance with your inquiry.
Good luck with your move.