The same technique used in the Brazilian Buttock Lift, which is called “Micro fat grafting”, could be used to add more volume to your hip area. The procedure would involve liposuction to another area of the body, such as the abdomen, and then these tissues would be skillfully injected to the hip area in order to create the shape you desire.
Keep in mind that your recovery period may be a bit more difficult. You will not only have to avoid putting pressure on your buttocks, but also the side areas. That means a lot of time positioned on your stomach, and a commitment to about 3 weeks of these limitations in order to ensure the best chance of success with the grafts.
It is important to have a discussion with your Board Certified Plastic Surgeon to ensure you both are on the same page in terms of goals and realistic results.