My 9 year old butt implants are uneven. Is a BBL to one cheek possible? (photo)

It is essential to learn more about your history. Since when do you have that uneven appearance? If that is something new maybe it is better to have an MRI to evaluate implants position and condition. Fat transfer to one side is always possible if you have enough fat to fill the gap. But you should be aware that %40-60 of the fat that is transferred will survive in 3-6 months which means that you may need more than 1 session to get a permanent volume
I hope this information would be helpful

Based on the 1 posted photo YES! lipo of areas upto 1 liter of donor fat can be attained with transfer to 1 buttock. BUT, always a but, I require an ultrasound of the buttock to see if butt implants on larger side dislodged, rupture on smaller side, if in stable position. I offer this examination in my office or you can obtain an RX for ultrasound examination. I charge of ultrasound examine $500. If satisfied with the ultrasound examine then surgery can be offered fee $5,000. Best to virtual consult with....