This was a ya book about a teen model who lived in New York. She had a friend that she went home with and met her brother whom she liked. I believe her mother had moved to NY with her leaving behind her father and her brother in their home town. I looked through all the others you have posted and none matched. I already checked out the All That Glitters books and hey do not match either. Help would be appreciated!
Lost Classics of Teen Lit: Name That Book! 
Sounds like a book I used to have called Paper Dolls. There was also a tv series, but I don’t know if the book came before or after.
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Maybe one of the Cover Kids series by Suzanne Weyn? The first one is called ‘Nicole’s Chance’.
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