As they get older, the elder children continue to help others and to set an example that the younger siblings can learn from. Be careful not to give your eldest ones too much responsibility, though. At this age, they can’t take care of a sibling by themselves.
Give them small tasks, such as pushing him on the swing, helping prepare a snack, or teaching a game. But never leave them physically responsible for the sibling by allowing them to do such things as take them around the block without you to play with the neighbors. And don’t ask the elder ones to do too many chores for the sibling, since this can foster resentment. The former may feel that they have to do all the work all the time, and your younger ones may resent not being able to do things on their own.
Always reassure your elder ones that they’re special, and that you love them. When you talk to them, acknowledge their feelings. Expect some regression now and then, and don’t chastise the elder for having negative feelings about younger siblings.
Above all, be sure to give your elder ones that one-on-one time each day. It can be hard to find time to be alone with each of your children, especially if you have a baby, but even 15 minutes at bedtime can help to make them feel special.