Can I get a second round BBL if I already have fat necrosis?

Dear Giving951,it is hard to tell for sure without an examination. If you are considering surgery, I would suggest you consult a board-certified plastic surgeon. Only after a thorough examination, you will get more information and recommendations.
Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery

Without series of good photos it would be very difficult to give your sound advise. In general, combination of liposuction and fat grafting is good treatment for secundary deformity after BBL. In person consultation or teleconference with a board certified plastic surgeon with known expertise in BBL revisions is recommended. Good luck.

Allow me to answer your question as best i can without any photos. However, please keep in mind that an in-person, or at least a virtual, consultation with physical exam is first necessary before any legitimate evaluation or final surgical recommendations can be made.

You are in good company with many others who had high hopes for BBL but instead received disappointing results (lumpiness, unevenness, lack of projection in the central and/or lower buttock, insignificant hip augmentation, post-deflation sagging, fatty necrotic cyst or scar tissue, etc.) as most of the fat melts away. It is not quite as much the quality of the doctor nor liposuction technique but rather the quality of the procedure that is a large part of the problem. Thus, going back for additional rounds of BBL most often produces the same disappointing results but at another financial loss. Beware, if a surgeon asks you to purposely gain weight (i.e. fat) before BBL, know that the fat you lose first as you get back to your baseline weight after surgery is that very same fat that was transferred into your buttock, hence your new buttock shrinks first, the fastest, and the most...so please do not fall victim to this recommendation.

Fillers, such as Sculptra and hyaluronic acids, for augmentation of the buttock/hips are a rip-off, period!

Buttock/hip implants, however, provide a more reliable, predictable, relatively safe, and permanent result, especially for adding projection to the hips and central buttock, and often help smoothing out lumpiness. Occasionally a lower buttock tuck may be advantageous for lower buttock fold asymmetries and/or sagging. When considering buttock implants make sure that the surgeon is going to be placing the implants within gluteus muscles , (a.k.a. “intramuscular pocket”), and that they are using anatomically correct, oval-shaped implants, such as Stanton Anatomic ®️ implants.
Please keep in mind that an extremely few number of board-certified plastic surgeons specialize in these buttock implants so be sure to consult with one that is reputable and experienced. Unfortunately you may have to travel long and far away from home to find this particular surgeon. Glad to help.