My two girls also are just 21 months apart. Trust me, it is true what they say that later on they will love one another and play lots with one another. So it is just a phase. What I am doing now with them is different, but when they were babies I also avoided leaving them together unsupervised, as pps said (sling, taking dd1 everywhere with me, etc). Recently, I also found this article, which I wish I had read at the time.<br><br><a href="http://www.naomialdort.com/articles.html" target="_blank">http://www.naomialdort.com/articles.html</a><br><br><div style="margin:20px;margin-top:5px;">
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<table border="0" cellpadding="6" cellspacing="0" width="99%"><tr><td class="alt2" style="border:1px inset;">When he hurt his brother, I would stop him gently, give love, and say "You are a wonderful person. I see that you want to hurt your brother. It is normal to feel that way. I love you just the same when you are hurting him, but we cannot hurt him. When you grow up you'll be able to control yourself. For now I'll help you."</td>
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mmmmhhhh... makes you think....<br><br>
One last thing is creating moments in which you leave them together purpusefully (I know, I am contradicting myself, but life is just not linear). Like when the baby is fed, and happy, and your eldest is in good spirits, you can put them both in your bed, or better on a mattress on the floor and just let them enjoy one another with as little intervention from you as possible. You can really turn this into a "love ritual". Show your eldest you trust leaving the baby alone with her, indeed, show her you trust her caring for the baby all by herself (you can still supervise from a distance, trying to busy yourself with other things at the same time).<br>
Hugs and enjoy your babymooning...