Looking for a shoujo

I've been searching for a specific shoujo from my childhood for a while but I don't have much informations other than what I remember from the plot.

It was about a brother who was secretly in love with his adopted sister. The fact that she is adopted is a secret to her and the parents don't know that the brother knows. The brother doesn't tell her right away but he appears to be a bit too tactile sometimes.

I remember that they end up together, they have a child and one of the parents, or the two of them, become a model/models.

Does someone have any idea what it is ??

PS : it's not Boku Wa Imouto Ni Koi Wo Suru