The best way to augment the chin is typically by bone advancement or with placement of a solid implant material (which appears to be what you had). This is true because the majority of the chin is bony and it is necessary to provide a solid augmentation that will assist the lip muscle function and yet also firmly support the chin tissues to prevent drooping over time. Chin implants come in pre-made sizes, and quite often, especially in women, the chin implants can be too wide for a patient who needs significant projection. For this reason, different types of implant shapes are available. I have learned that the typical large chin implant (extended anatomical type) is too wide for most women; as a result, I often use a medium extended implant and add an additional implant termed a Glasgow wafer to add a few more milimeters of projection without widening the chin. An alternative maneuver would be to simply carve the implant (yes, this can and is often done) to make it narrower and contour to your chin shape better. I would be much more likely to recommend that the chin implant be removed and carved or replaced by a better implant design than proceeding with fat grafting. Fat grafting is itself fraught with issues, such as a typical 50% loss of volume over the first year. In addition, placing the fat into the implant pocket may create additional issues as the fat would be positioned in between bone and capsular tissue, both of which may be less than ideal to provide the fat with the blood supply it needs to survive. Finally, augmenting the chin with fat would make it larger but not stronger, and over time it may droop, creating a "witch's chin" deformity, which you may already be at risk for given that you have already undergone chin augmentation. Please discuss all of these factors and treatment options thoroughly with your surgeon before deciding on which therapy is best for you. Best of luck.