Standard disclaimer: I'm not a lawyer, nor do I play one on TV, but I have tried to research this question a little

I don't think there would be any CP-related charges against the other models, since presumably everyone is operating under the assumption that the model is of age, and in most cases, the models are simply participants and not involved in the *production* of CP per se, so there would be a couple layers of "removal" from the crime there.

However, depending on the state, it is theoretically possible that the other models could be charged with statutory rape or contributing to the delinquency of a minor or some such, but I suspect that it would be pretty unlikely that either the Feds or a local DA would bother with such a thing, unless they were using the threat of such to, um, "encourage" cooperation in the investigation.