Add-on User Banning- Warning system

Basically I'm looking for a warning system, for a gaming server I've started up.

Say a user gets banned in that server/game, they can appeal for it on the forum, when appealed and accepted they will get a strike next to their name, indicating they've been banned before, for future reference if say they get banned again.

Here's how I think I'd like it to work, at the bottom of the users posts (every post they make) there's a button called "Ban Appeal , when press on, only by moderator/administrators, it will then put a little red "[]" box above their user name.

This will indicate that this user has been banned once/warned once by the admin team, therefore other users are able to see this indication above their forum name.

Screenshot Examples (Not a real picture of what it should look like, just a draft):

Thanks a lot,