My doctor says she can't inject Radiesse into jaw line

I keep seeing information that radiesse can be injected into jaw line for more definition and to pull back skin from buccal area? She says that means it's injected into the cheek which pulls the jawline more taut.

I had my cheeks augmented with her and I really like the results but I still want maybe a millimeter of definition at the massater area. I hope I am making sense. I am 28 and look very young. My goal is contouring and pulling that area (jowls?) around my mouth back.