Infants don't do much (but I sure love them). Once Kiddo figured out the baby wouldn't be playing with her, and instead took up a lot of my time, she wasn't sure how she felt about her. She was sure excited when Baby cried ("the baby is cry-ning!"), but thought our loud shushing her to calm her ("dada is being quiet") was a little weird.
But now Baby is fully integrated. When we leave church, Kiddo calls out "Come on Mama, Come on Dada, Come on Baby" which always makes me smile, as if Baby had a choice about her participation. And at night she says goodnight to me and her individually. And it's been at least a week since I've heard "Mama will put the baby in her swing, and [interaction of choice with Kiddo]."
(Oh, and did I mention she had her first in the bathtub bath?)