So much hate, rage and negative thinking are not good for you.
You are a 10 year old girl, where are your parents?
Are you having a combine family system?
Where are you chachu he knows about everything you mention.
Please this is not your problem give the chance to the elders to solve it.
Some time when you live together you have some complains about each other.
If she does not know some of the rules of your house teach her with softness she will learn it then behave like as
I hope you will understand.