Is putting the breast implants closer together by cutting muscle in middle of chest and also repositioning nipples safe?

If your implants are underneath the muscle often times more medial dissection has to be done to create greater cleavage. However, it is possible to actually cut the muscle and then the implants will extrude medially and create symmastia, which is not a good result. Unfortunately, you have not provided photographs but there are alternatives. One option is medial fat transfer and another option is a breast lift done simultaneously.

Best Wishes,

Gary Horndeski, M.D.

Dear FairWanderer,
I almost always place implants submuscular. It lowers the rate of capsular contracture significantly. In addition, it looks much more natural because the muscle provides covering over the implant so its not as round on the top. I've also noticed the implants drop less over time when they are protected under the muscle.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

If you're having a lift the nipples get moved anyway so they could be moved. But if it's just implants, moving the nipples is not a good idea because if the scarring that would be involved

Your surgeon should have discussed the risks with you during the consultation and has probably given you written information about the risks. Ideal implants are still saline implants and can still have ripples. Not all of your muscle will be cut, but just some on the lowest aspect of your sternum. Adjusting the nipples is good if needed. You still may sit somewhat far apart because of your anatomy.