Sure. What I want is basically this.
User "Leo" is a moderator in the forum "General Chat."
User "Locke" is a moderator in the forum "General Music."
User "Leo" will post in "General Chat," but he will not be marked as moderator on that post. User "Leo" will be marked as moderator if, and only if his post is in "General Chat." User "Locke" will be marked as moderator if, and only if his post is in "General Music."