OP I have the same problem with my 6 year old and my 3 year old. I don't know what to do either, I have resorted to making my child to handwriting (I will not be mean) when he won't stop.

Sometimes you have to give someone a taste of their own medicine, and it won't damage Op's DD.

OP, this is part of being a sibling. You come home and metaphorically kick the dog. You take your frustrations out on those around you, those closest to you who you know will love you anyway.

How is this different from hitting a kid to show them what it's like to be physically hurt? Or do you agree with that?

After you try everyone else's sweet and loving ideas. Try this: Tell the 8 year old that for one day you are going to treat her how she treats her sister. At the end of the day ask her how she felt. If she tells you she doesn't care keep at it. You can't make them like each other but you can show her what it feels like.

My 8 YO DD is just being plain mean to her 4 YO sister... how can I get her to be more kind? The "How to Talk So Your Kids Will Listen" version for siblings is second-nature in our house. Often the 8 YO's behavior isn't "technically" rude, but it's just not nice at the same time. 4 YO tries and tries to be sweet/generous to the older sister (although the 4 YO isn't totally innocent, either). It's really hard to watch.

Any ideas?