I need advice please

First of all, I’m not a parent. I’m a sister who is trying to help my little sister.

Our mom couldn’t be bothered to parent her or give her emotional advice. She doesn’t have the capacity to teach her without being a narcissist.

My sister is 16 years old. She started making friends online (tiktok) asking for a friend because she told me she’s lonely and her friends are kinda leaving her behind. She linked her discord. And made a video saying she’ll talk to them whenever and call them all the time. She told them her age…

The problem is that all her new “friends” are all male. Massive red flag already. I have tried so hard to tell her how wrong it all feels.

She doesn’t wanna hear it. She says they’re way more fun to chat with than girls who befriend her.

I feel so hopeless right now.

If I force her to stop, she’ll just be sneakier about it. Our mom is useless. What do I do??