I come from a family of 10. We are sort of seperated by age into two groups. I am the sixth and oldest of the younger 5 (all boys) I am 5 years younger than my next older sibling (A sister)
We use to use my youngest brother as a test piece. When we went swimming we would thro him in (He was about 4 I was 8) and if he came up we knew it was safe to swim.
I have a million stories to tell about annoying siblings. They get better with age mainly because we grow up and move away from them.
Good luck with your sister. But remember this, you choose your friends and they can choose you but your family is forever, so look after them and cut em a bit of slack once in a while. They\'ll appreciate it in the long run.