Canons and OCs shall have a signature but to tell the differences between characters. It should include character name, Age and Occupation. For example:
1st Character-Age-Occupation
2nd Character-Age-Occupation
3rd Character- Age-Occupation
That's how it should be to avoid confusion. In addition, for your canon app, you should also write a quote that your canon says. Like for Sebastian, you could write: "Akuma shitsuji deska~" [trans: I'm one hell of a butler."] You can decide what quote you want to use.
Thank you for cooperating and I hope each and every member is doing their part in recruiting new fans! <3