Unfortunately not ANY Skyteam. CO can't be mixed with KL for example, I had the luck sometime that I asked for availabity AMS-YYZ-AMS. The lady of FB could give me an option for AMS-YYZ with KL and YYZ-AMS with CO. When I called back to confirm, it was not possible to confirm this because this combination wasn't possible. They changed me then to KL for both legs, although there weren't awardseats available on KL, because it was clearly their mistake.