M.:
Hello! I'm truly sorry you are going through this.
Ground rules must be set up for everyone in the house. The rules must apply to everyone and there must be consequence for negative actions. A family meeting would be a great way to set the ground rules and what the kids think is fair punishment for their "crimes".
The rules are simple in our home:
1. If it's not yours - don't touch it.
2. Do unto others as you would have done on to you.
3. No means No.
There are others but these would be the two that apply to your home.
Your 13 year-old is going through a ton of hormonal changes - but that doesn't give her the right to get into an actual hair-pulling, pushing fight with her sister or anyone for that matter. She needs to learn anger management. Do you know the friends she hangs out with? If not - do and find out about their families too - she may be learning this behavior from them.
My suggestion for her would be to help her adjust to her changing hormones by giving her one-on-one time and letting her know that her mood swings are typical but not acceptable. She needs to learn to take a deep breath and back off. A school counselor can help with this as well.
If your daughter's share a room - separate them if possible. Give both of them their own space. Get baskets for their bathroom to put THEIR stuff in. If one steals - she pays for it and gets grounded - or whatever punishment will work in your home.
They need to be reminded they are setting an example for their younger brother - is this what you want him to learn?
Target has inexpensive baskets - let them pick them out for themselves and ensure they know whose items are whose and realize they are NOT to touch, take, borrow, etc. whatever will get the point across. If they want to use it ASK THE OWNER FIRST and if the owner says NO - NO MEANS NO..
I hope this helps! God Bless!
Cheryl