I just read the other posts and they are all fantastic.
I do agree withtrying to involve the older sibling as much as possible with the care for the younger sibling. IF she is interested. My DD loves babying her little brother. It gives her something to do and no chance to misbehave. I let her dry his bottom after a nappy change, get a tissue (or 10) when he has vomited, put cream on him after a bath, wash his belly in the bath (they usually bath together), give him a drink from his sippycup when I'm feeding him his solids. When I BF him, I let her sit next to us and cuddle and we talk about his toes, try counting them, belly button, whatever. She adores him, which helps. Or we play a game were we take turns and try and make him laugh by pulling funny faces, making silly sounds etc. She is so proud when she can make him giggle. And she gets LOTS of praise for every lovely interaction she has with him.

Just because your first child acts up, it does not necessarily mean it is jealousy. It might simply be boredom. Boredom can be almost painful for a young child.

Alex
xx