Chat Tab Options
 

Is it currently possible to add a custom filter to the standard Chat Tab Options list? That's the one that you get from right clicking Chat -> Options.

Second, what the best practice way for routing a message to a specific filter? For example, redirecting CHAT_SYSTEM:AddMessage(msg) to NPC rather than default System. I've only been able to find ways to make a completely new window that mimics chat behavior and output text buffers there instead, and AddMessage seems to only take AddMessage(string message, r, g, b, colorId) as arguments. I'm assuming there is something like local myCS = CHAT_SYSTEM:SetBuffer(CHAT_CATERGORY_NPC). Or maybe making a new control from scratch is necessary.

I'm really just trying to output TextAreaBody to a chat tab for the player to see, without spamming every tab with the default System filter enabled, so NPC would be the best alternative if a custom filter isn't possible.

Another approach might be to have a setting from my LibAddonMenu panel that assigns a tab# as the target, where the user is responsible for making sure they have at least that many tabs if they want it to work (i.e. send it to tab #3 from the left to right).