My friend suddenly decided to nurse on the 4th day, and is still giving formula. The baby does not seem confused by the different nipples. She took right to the breast and still likes her bottle. I have never seen this before. I breastfed successfully but avoided all formula/bottles from the first day. She is a young woman who is interested in breastfeeding, and suddenly decided that she just must try it. She likes breastfeeding but does not want to do it exclusively. I recommended that she nurse at fairly regular intervals so her supply will meet the demand. Has anyone heard of another similar situation? I admit I am thrilled that she has changed her mind a bit. Bottles are a huge hassle, but convenient so others can feed the baby.