How Are Breast Implants Implanted

How will pregnancy effect Breast Implants and is breastfeeding possible?
My soon to be sister in law has breast implants and my hubby and I were talking about what would happen to them when she becomes pregnant. And can you breastfeed a baby when you have implants? My breasts changed a lot with all of my pregnancies and I am sure an implanted chest will be changed too. What is the long term effect? Will she need another surgery in the future?
My friend who has impants had triplets in December…..while she was pregnant it didn’t affect her implants, but her breast did swell and get bigger…and in fact she does breastfeed. Her implants are the ones that go under the muscle. Her OB and pediatrician both ok’ed it too.
She may need to get them lifted if her skin stretched so much that they sagged, implants just have always looked weird to me when they start to sag. or depending on her size, and the size of the implants and if and how much sagging occurs she could also go up in size with the implant to fill out the skin.
Blue Marlin impales woman’s breast implant