She told me that when you are adding another child into the mix that the toddler should be as involved as they can be with the new baby. If the baby is crying and you are doing something with the toddler you should wait for the toddler to notice the crying. That way they would be the one suggesting that something needed to be done instead of you just dropping everything to take care of the baby. The baby will not remember crying for a little bit longer but the toddler will remember being pushed aside in favor of the baby.
I have applied this advice and I really think it has helped a lot. Evan and Harry are generally pretty good friends. They are not so great about sharing but they are also not fighting all the time and are often very friendly and loving towards each other.
Go check out what others have said and play some of the baby shower games. See if you can pick out my baby picture.
They didn't even fight!