If a user leaves their “full name” blank, then the only thing you’ll see is the username. Some users may only fill in their first name, some full name. Unless you make it a required field, not everyone will comply. 
If a user leaves their “full name” blank, then the only thing you’ll see is the username. Some users may only fill in their first name, some full name. Unless you make it a required field, not everyone will comply.