Update for members planning ski holidays in Sestriere (or other Vialattea sites) who are looking for information about the validity of doctor letters to use as recovery certificates for minors age 12-15:

I've made multiple phone calls and written two different emails trying to get information. I'm getting a bit of a run-around at the moment; it seems no one wants to answer other than saying "you need to check the government websites."

I'll keep trying to track down a definitive answer yes or no.