Step 1: Drop your sister off at your local second hand shop
Step 2: Get a new sister. I would recommend K-mart which gives you a DIY kit filled with all the parts you need for a sister. You’ll just need a screwdriver and batteries. Also stocks in brother version. This is an optional step, you can stay only child if you want or take out sweet revenge on your new sister.
Step 3: Enjoy your newfound life and freedom.