Sacral dimple incision or fat grafting? (photo)

I would excise the dimple. This would leave you with a hair line scar but would fix the dimpling.  A fat transfer may not work in this case.Please be sure to choose a Board Certified Plastic Surgeon who specializes in this procedure and is well known for it.

This is something that would have to be examined in person and determined whether sacral dimple excision with buttock cleft reconstruction is worth the end-resultant scar. Glad to be of help. 

The sacral dimple formed early in an Embryological state. The midline fuses while coming together from both sides during this phase of development. In some people the midline fusion is incomplete leaving people with a dimple, pilonidal cyst or in its worst form spina bifida.
It will not respond by adding volume with fillers or fat and the only realistic treatment option is direct excision.
This can be done By a plastic surgeon or general surgeon. If you see a general surgeon I think you’ll have a better chance of having them build this to your medical insurance and not having to pay for it. Perhaps your dimple gets “ irritated“ from time to time. perhaps it causes locational discomfort?
A plastic surgeon will most likely only except cash payment and declare this as cosmetic because insurance reimbursement will only be a tiny fraction of what our customary fees are.
Pilonidal cyst’s are typically Taken care of by general surgeons but plastic surgeons are sometimes asked to help when they are complex or previous attempts have failed.
That condition is more complex than what you have.
Your situation is actually more complex that it may seem on the surface because of the origin but I think you can take home the bottom line that surgical excision is the best option.
I think you need to Accept your natural gluteal crease and not attempt to incorporate or change that. I think the outcome would look unnatural and disfigured.Best, 
Mats Hagstrom MD