Lift with existing implants? is it plausible to do so using my existing implants, placing them sub muscular?

A breast lift is done to correct the nipple position and reduce extra skin. It sounds like the implants are filling up the extra skin. A plastic surgeon would have to look at how much extra skin is available and if your breast position meets the criteria for doing a lift. I personally would not advise using the same implants due to the size and weight.

Yes, as long as your implants are in good condition (they should be at only 3 years old), you can absolutely get a breast lift and have the implants placed under the muscle. If you would like to be seen for a consultation to go over lift options, feel free to reach out to my office. Smith Plastic Surgery 7”2-838-2455

There is no problem performing breast lift over implants. However, considering that your implants are already 3 years old you have to decide to leave them where they are (on top of muscle) or place new set of implants underneath the muscle. I do not see rason for moving the implants since you are happy with result and breast lift is going to be performed over the implants. You should discuss this issue with your surgeon ahead of surgery. Good luck.