The name of the song you are looking for is simply "The Baby". It is performed by Blake Shelton and probably is one of the saddest, prettiest songs I've ever heard. Although I was at my mother's side when she passed away, and I am the oldest of 7, I still cry every time I hear it. My "baby" brother and I held each other and cried until we didn't think there could ever be another tear in the world.