Whatever they are, they'd have to both be beneficial to Winter. I think the only reason Maeve was able to suggest going against Mab in CD was because of her infection. If the Queens are all tied to Winter's purpose, then they can't conflict in that aspect.
In other Sidhe news, there was confirmation that Maeve did sexual things, but never had intercourse, and Lily and Fix weren't together sexually either. The maidens might have some loopholes in their activity, but loosing their maiden-status wasn't one of them.