Is it OK to have an explant, lift and fat transfer at the same time?

I perform breast lifts after implant removal regularly. I am always pleasantly surprised at the final size of the breasts after the implant is removed and the breast is reshaped. It is usually quite satisfactory and looks youthful and attractive. It would be rare to have poor aesthetics and contour irregularities especially if your doctor is doing fat transfer as well, although you may need a second session of fat transfer to get the desired results. I would recommend you trust your physician and if he or she feels they can deliver a good outcome, I would go with that and not listen to anecdotal reports from people who don't have a large experience doing this.

There are several factors that determine the result of a breast implant removal. Your skin could stretch back under several conditions: (1) if your breast tissue did not decrease over the 9 year period from your original breasts; (2) if your pectorals major muscle maintained its bulk; (3) if your pectorals major was not cut during insertion; (4) or if it was cut during insertion, it was repaired successfully after explantation; (5) if your rib contour was not altered by the implants. In other words, your skin has to be supported by adequate volume in the breast. In general, breasts with sub pectoral implants tend to do better than sub glandular implants after explantation, because the breast tissue is less stretched by the implants. Breasts that had no contracture tend to do better. Your question is a good one but complicated to answer without more information. Linked is my webinar about all of the factors that contribute to the aesthetics of an explantation. I also discuss fat transfers, both small volume as well as large volume. 

Before making your decision it is important that you are comfortable and confident in your surgical plan. I encourage you to speak with your surgeon about your concerns and understand the pros and cons of the planned procedures. It is unlikely that you will be able to match the volume that your implants provided with a single fat transfer. I do not prefer fat transfers to the breasts as microcalcifications may form which could interfere with future mammograms or other breast imaging studies.

When I perform en bloc capsulectomy and implant removal I dont perform fat grafting because there is not a suitable structure to place the fat around.  You cannot simply place it in the previous implant pocket.  It will not survive that way.  A lift can always be performed at the same time if necessary.  Usually a periareolar lift is adequate.