Yay, I found this one while looking for the fic where JR calls Brian "Daddy"! (Don't think it's the same one but wouldn't swear to it. She calls him "my Bi" in this, but maybe she switches to "Daddy" later??)

It's Cyn's Just Like Family series. Milestones, which I think is part 4? The series is in the GIH fic folder.