When dealing with sibling rivalry it is always important to be fair andnot jump to conclusions. It is also very important to remain neutral. Onemust also deal with conflicts objectively, so as not to allow your ownproblems get in the way and worsen the conflict. These rules go for bothparents and baby sitters and should always be kept in mind when dealingwith such situations.
One of the roots of sibling rivalry is jealousy. Another is fear. When therivalry is between a baby and a toddler it may be because the toddler isjealous about the attention his brother is receiving or out of fear that hewill receive less attention now that his mother is caring for his brother.
In such a situation the older brother may act violently toward his youngerbrother in the absence of an adult. In such a situation there are differenttheories about what to do. Some say that a parent should allow them to workit out by themselves (unless the baby is too young). The instinctivereaction is to scold the older brother and “baby” the younger brother. Thishelps neither brother. The younger brother feels more dependent, whichdamages his self-image, while it makes the older brother resent theattention his younger brother receives even more.
In this situation my personal belief is that a person should calmlyexplain to the older brother that what he did was wrong, but forgivable.
You should also explain why it was wrong in a way the child can understand.
In my opinion the worst thing a person could do in this situation is toforce the child to apologize. It will reestablish that what he did waswrong, and, since his baby brother is not able to respond, will make himfeel even more guilty. The apology will also be insincere unless it isexplained to the child why what he did was wrong. The guilt the child feelswill also be translated into a facade of other feelings. I believe it ismost likely that the dominant feeling would be even more anger toward hisyounger brother. In my opinion, older children would be able to work outtheir arguments for themselves if they are separated and forced to presenttheir reasoning (with the help of an adult to translate).
Punishment is also a hard topic to deal with. Not giving punishment wouldtell a child it is okay to bully someone weaker. A harsh punishment wouldonly amplify the tension between the siblings. I believe that punishmentsshould be fair, and, when assigning them, be sure that the child beingpunished understands that he is not being punished because of his brother,but because he knew his actions were wrong and committed them anyway. Ifthe child was ignorant that his actions were wrong, I believe you shouldexplain to them why their action was wrong and suggest another way of withdealing with his situation, oppose to punishment.
Sibling rivalry is unavoidable, but can probably be lessened by treatingchildren equally, not jumping to conclusions, and helping childrenestablish a firm morale base which they adhere to.