It's maybe a possibility but Jeanne A. C is her name so maybe JAC could be her initials? Maybe it's a nickname? She is also in the Firm for Life book in the straddle stretch picture. She is in Maximum body Sculpting(in a blue-ish workout shorts and tank and they close up on her doing the delt fly) and Basic Sculpting with weights(in orange).
It's nice to see a new face
Mandy