Not sure if you've changed this to how it is now intentionally or not. But it has changed from how it used to be. IMO used to be much better.
Before you could /whisper (/w) someone and it would go into General Chat. Their replies would also come into General chat.
All group chat messages would also come to General chat to be read.
Now all /whisper (/w) messages appear in General, Realm and Group and give flashing notifications for each.
Group chat messages can not be viewed in General chat.