AIO because my new coworker has been stealing my tips

I have been in my industry for 4+ years, about 2 months ago we hired a new worker (we’ll call her Amanda) I also work with my best friend (BFF). A couple weeks in my BFF calls me saying she thinks Amanda changed some of her invoices because the number of customers changed and the credit card tips were less than earlier (specifically missing about $20) today, manager approached us (without amanda being there) saying another employee who closed with Amanda was missing $25 by the end of the night in credit card tips. Other coworkers mentioned how she’d seen Amanda messing with the invoices before, and had seen her change the names on the invoice but didn’t say anything because she assumed it was an accident. We are all now keeping exact written details of watch customer name, invoice number, total and tip amount.

Am I overreacting if I want to legally press charges if I do catch her stealing from me? I’m not even sure if I can, I have no way of proving how much she’s stolen from me/ us in the past.

TL;DR: New coworker is stealing credit card tips from us all, we have no way to see how much she’s stolen. If I catch her stealing I want to press charges so she has something on her record. Can I even do this? Am I overreacting and should I just let her get fired when she gets caught and not press charges?