I always use if and else statements, as I am to lazy to make 2 styles for each new style I have, lets say I have 6 styles, I will have to make 12 different styles just for that one forum.
or, you can switch around the template, make if/else statements so that if the forumid is 6 then the newreply will use newreplynew template, if not it will use the default one.
You see