Breastfeeding is a strange concept to an older sibling. Once they understand the basic idea they are more than open to talk about their baby siblings dinner options.
Having a new baby can bring all kinds of changes, not only for the new parents, but for any older siblings. My older son still makes me laugh with his observations about his brother. We were very open with him when I brought my baby home from the hospital about breastfeeding and the needs that a baby has. It was never strange for him because he didn't know any different. Just the other day my mother, who had spent a lot of time with my older son while I recovered, told me that she was eating with my son and asking him about his new brother. My older son apparently announced to everyone that his baby brother "was having boob for dinner."
I laughed and laughed. I had never heard him say anything and I have long since stopped nursing so the topic has not come up in conversation until now.
For information on breastfeeding for the first time read - Breastfeeding 101.
