The Brooks Brothers Unknown Sister (Janoskian Sister)

Isabelle Brooks is just your average 16 year old girl, She loves One Direction and The Janoskians, She lives with her father and is an only child (Well that's what she thinks) Isabelle thinks that her mother abandoned her at the hospital and left her with her father when she was a baby. But little does she know that her father ran off with her when she born and walked out on her mother (and her three unknown brothers).
What Will Happen?