Hi trinavogel,

I can completely understand how you feel.  I have two boys who are two years apart and there's nothing more upsetting to me than when they mistreat each other - that Mama Bear instinct comes out when someone hurts your kid...even if it's your OTHER kid!

I don't think you can eliminate sibling fighting altogether, but it sounds like you're family is experiencing an extreme situation.  We have some good articles on sibling relationships that I hope will give you some ideas of how to help your daughters.

http://www.education.com/magazine/column/entry/Fighting_Siblings/

http://www.education.com/magazine/article/Sibling_Revelry_Raising_Kids_Who/

Good luck and please let us know how things are going!

Kat
Education.com Community Team

It is very hard when you have siblings and one of them displays some undesireable behavior.  You as a parent need to do your best to show that you are consistent with your teaching and what you expect from both of them.  
There are a couple of strategies you can try.  You can pre teach self control, talking nice to others: giving compliments, showing appreciation, etc.  Also be specific.  You want your daughter to be rude and say mean things.  You can specifically tell her what she said and ask her to think of something else to say instead and try to do this calmly.  For example: "that made me mad when you used my pencil, next time please ask me" "do not take my pencil from me, please give it back"
Let them know that you will be trying to do somethings with them to improve their relationship and how they talk and react to each other.  Try playing a game with both of your daughters.  You pick the game.  You are there with them and can observe how they treat one another.  Then if your daughter decides to call her names or become upset: issue a consequence for her behavior.  She will need to apologize for the comment or when the game is finished she will write an apology note.  Ask her calmly to take a deep breath and calm herself down.  If she is unable to do this and her behavior escalates, you declare a game delay.  Take some time to breathe, count to ten in her head fast (do this for yourself also, as this will prepare you for what you will do next--also set up your other daughter before the game that you are working on being together and talking nicely with her sister.).  Remember to monitor your feelings, if you are frustrated: keep reminding yourself that this is their behavior and you want to address it and correct it, and try and separate it from your feelings.  This is difficult to do, but if you as a parent work on focusing on their behaviors, it will ultimately help you and them.  Try to resume the game, and finish it.
Try rewarding your other daughter for not feeding into the behaviors of her sister.  This can be very powerful teaching to both daughters, as you would be focusing on the positive attention as opposed to teaching to the negative attention--but do not forget to be consistent with a consequence, and be brief in your teaching.
And lastly, do not forget to remind them of the times that they get along.  Praise them when they are nice to each other, or help each other with their responsibilities/chores.  By focusing on the times that they are nice to each other, hopefully the times when they are not so nice will decrease.  Be consistent, patient and loving.  It will take time, but you will ultimately set them up for future healthy relationships and how to get along with others.
 
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Maybe your child needs more attention from you.Maybe she's jealous of something that you don't know.Children at this age has the ability to trust others and with the sense of respect for their own worth.Initiate a therapeutic communication towards your child.Ask her patiently of what's going on and her problem.Children may show empathy toward others as early as 20 months, but cognitively they cannot relate others' experiences to their own until about 6 years of age.Therefore, it is usually ineffective to lecture a child by saying,"That was cruel." The child may feel she had every right to do so. A better technique is to ask your child to put herself in her sister's place for a minute and imagine how she feel if she was her sister.

keep them as seperated as possible  on different rooms different table areas and have the 11 yr old talk to 7 year old about how she feels when these things occcur  time and age will change tihs also but they need to learn to communicate with each other on the same level  my 8 & 10 yr old have been the same and we are trying the talk to him not at him  there is a vast diffference and they may not know that yet  talking to   with  or at are all different venues  they need to learn which is which and find equal ground  guide them to what ever level they are comfortable wih  peace will rein sooner or later  but they need to learn to talk with each other    good luck  it does take time ti change this but you will see results