Sister Ran Away To Bf House While Their Family Hid Her There

Location: California

A couple weeks ago, my sister (17) had ran away from home while we were at the lake. She got upset because my mom said that her boyfriend couldn’t come with us to the lake. So when we came back and noticed that she was not home and that her clothes were missing we made a report on it my mom had texted everyone she knew and also told my sister’s boyfriend’s mom if she had heard anything but she said no and never updated my mom. We all knew that she was going to run away to her boyfriend’s house, but the next day we were asking our neighbors for footage of her leaving.However, all we got was that she was going around asking to use different neighbors phones to call him so we knew for sure she was there. So my mom again reported that to the police. My mom ended up calling the boyfriend’s mom again but his little brother answered saying that she was asleep even though it was around 8-9 pm. The next day after that my older sister, her boyfriend, and I found out what apartment they live in and went to knock on it and the same little brother who answered the phone, answered our knock and we asked him if our sister was there and he said to hold on. He proceeded to close the door and then tell us that she was not and that his mom and the boyfriend were sleeping. We thought he was acting suspicious so we went back to the car and called the police. The cops came and confirmed that she was in there and gave her us back. My family was not happy with what his family had done and assumed that the mom could be charged with harboring a minor but the cop had said that in this case it was not.

So, can someone please explain to me why it wouldn’t be? I feel like the mom could have told us within the 2-3 days that she was gone, but instead kept her within her home.