Yes! Press charges.
You will never know if or what it will take to help her, but she shouldn't get a free pass for illegal activity because she is using.
She is more likely to change when she is made to change or has a reason.
It's not your job, her mom's, or grandma's to protect her bad/illegal behavior because she's stealing for drugs.
Stand your ground, don't let the drug addict in her lead you to protect her addiction.