There are a few things I am confused about; if Nelle was like 6(that is the age she seemed to be in the flashbacks) when Carly was 18 or 19 then how could she have been a child when her father donated her kidney to Joss.
When Joss was born Nelle would have been an adult when Joss was a baby. She probably wouldn’t have been able to donate her kidney since Joss was a child and she was an adult.
Carlys age and Nelles age don’t make sense according to the flashbacks.
Also who is Nelles mother? I don’t remember her ever mentioning a mother.