In case you have described, you have several guilds. And many users has different names accross games, so the solution is you put all Guilds into RP, enter all characters (in every game, guild) assign them to users.
All raids can be connected to guilds (and therefore can be game specific), and only characters in that particular guild can be set for the raid.
Since 0.7 game (theme) can be setup for guilds. What’s wrong with this?