We have a 2 1/2 year gap between Wolf and Bear. Before Bear came home Wolf got his own baby doll with bottles and diapers, etc... He could take care of his baby while I took care of his brother. There was also the explanation that when the baby gets a bit older Wolf could help more. He could teach him to talk, try to make him smile when he was crying, play with him, teach him all about everything. The getting diapers part helped too. In the meantime he could help by helping Mommy, getting a blanket for nursing time, being quiet when the baby was sleeping, being a good boy to keep Mommy's stress level down, etc...
What we found though was that once Bear was home and Wolf realized that he was just a loud, smelly, Mommy time sink he became much less interested with the baby. When Bear got to the more interactive stage there was a golden time where Wolf would make faces to get the baby to smile and bring him toys and pick up what he dropped. Then Bear became mobile and went after his brother's toys and the novelty REALLY wore off.
