We dont have any nicknaming traditions in my family, I prefer full names but dont insist upon it I tend to think that it is up to the children themselves and their peers what nn if any that they go by.
Though I admit I did point my neices and nephews away from the nickname
Cathy for my daughter as I dislike it intencely, that said if
Catherine suddenly said that she wanted to be
Cathy I would accept it.