HilaryWitt
Louis and Harry are the adoption parents of Zayn, Niall and Liam
They adopted Zayn when he was 4. Niall when he was 3. And Liam when he was 18 months
Liam was born premature and has a weak immune system.
There's no real time frame to when these stories are taking place. So just imagine them happening between the mid 2000s to early 2010s.