The first night after we came home from the hospital with my 2-year-old daughter’s baby brother, I was irrationally determined to carry out a cherished routine. Every time I had ever tucked my little girl into bed, I sang James Taylor’s “Sweet Baby James” — but that evening, her bedtime arrived just as my newborn demanded to nurse. I made a choice: I handed my wailing infant to my husband and dashed into my daughter’s bedroom to say good night in the way she’d always known, as if nothing had changed.