hmm, interesting theory. By the way, there is no such thing as ''middle name'' in French, they are ALL ''given names''. And the man created as Jean Baptiste with Baptiste used as LNAB is set to merge into his correct name at birth and all his wives. He was Jean Baptiste Baudreau.
Doesn't need to be an execution for kids to go by another name, the mechanism of ''dit names'' are multiple. Sometimes the son or daughter will be listed with the parent's given name as a dit name, like Jean Joubert ''de'' Jacques is how it starts (Jean Joubert Jacques's son - or of Jacques for literal translation), and it then becomes Jean Joubert ''dit'' Jacques (called Jacques), and then next generation somebody omits the Joubert and the kids get named ''Jacques'' as a last name at birth.