Guy I'm seeing daughter wants me to tell her dad to let her dress more mature

Okay guys this is another update. I had made a post about whether or not I should give this guys a chance. He has 4 different kids but 4 different women. He has custody of all of them. 2 baby mamas passed away, one from drug overdose, one from child birth. one lost custody for drug related reason and another one he won't tell me how she lost custody because it makes him mad. So i gave him a chance and did end up accidentally meeting his kids. max is his only son who is 16, maddie is 14 clair 12 and Amber 8. they just think I'm there dad's friend.

I was over today and Maddie asked if she could talk to me in her room. i said yes. My boyfriend was out working on someones car(He's a machanic). So she started high school this year. Every years my boyfriend goes out and does the back to school shopping. The kids usually stay home because they hate trying on stuff. She said she got bullied because her dad dresses her like a little girl. I said she's 14 and there's no need to dress revealing so young and she said that's not what she's talking about. She opened her closet and showed me some clothes my boyfriend got her. On was like one of those little tan kaki dresses that you wear a shirt under and the shirt that she was wearing under it at school was a shirt with bunnies on it... Then a pink shirt with a skirt that said Sunshine and I'm hear wondering how he found close in these sizes. Then she pulled out her shoes. They had sparkles at the toes and I said "Plz don't tell me they light up". and she smacked them on her dresser and said "They light up!" As they lit up. I asked why she didn't just tell her dad she doesn't like the clothes and she said she doesn't want to hurt him feelings... And asked if i would do it.. She said she isn't trying to dress revealing or anything, but mature. We've been seeing each other such a short while. How can I bring this up to him for her. I honestly just think he has bad style because his son Max hates a lot of his clothes too. One of his shirts looks like you would where it on a Hawaii vacation..