Heyy. I’m trying to post the idea here since I was having problems commenting it in the book.
So, it’s Gip Bey
And it's like a 90s set when Beyonce's and Nicki's mothers are attached to the hip, they were best friends but when the girls are around 13(Bey) and 11 (Nicki), Nic's mother dies (she was an immigrant and was the only family in the US), so Tina doesn't think twice and get Nicki to start living with them, so they are like basically sisters now. But due to bey being older, they basically live separately for the next years, Beyoncé (GiP) is discovering herself, is popular and at 17 she finds herself jealous of Nicki starting to go out with her friends
Nicki is a sweetheart but she starts developing and needs to deal with bey's bickerness while her friends tell her how her older sister is attractive.
Since they live in a small town, their friend groups know each other and Nicki starts going to the same parties as Bey.
Well, someday their fights lead to them making out and they start to grow feelings (while Nicki looses her virginity to Bey and they are like rabbits around the house with the family noticing).
(Optional plot) Until Tina finds out and it really breaks her heart because she raised them as family. So she sends Nicki to a boarding school abroad or to Trinidad, and they never speak again until they are in their 20's.