I have a 9-month-old Rott that bit my daughter at 3 months. Since then, my daughter has said she's been bitten or at least scratched. How do we address this issues?

Hello my name is Angie, I was searching around online and found your site and had a similar situation. I have a 9 month old rott and when she was a puppy, about 3 months, she bit my daughter while eating a bone. My daughter had dropped something by her reached down to get it and she bit her lip. Since then, my other daughter claims she bit her head while she brushing her hair next to her and just tonight my other daughter, 5, was trying to hug the puppy and she said at first she bit her but then said she just scratched her face. Now looking at her it didn't seem like a bit but I'm not sure. What can I do to make sure this isn't really happening over and over again. Are me and my family over reacting and is she really just being a playful puppy or do I have a real problem? Anything you can suggest that might be helpful I will greatly appreciate it.