Better Chat is now Compatible with the Mod Communication Interface!
As such you can send Messages to the Chatbox of Specific Players easy & on the fly!

This is what you will need:
Bind in the ModCommunicationInterface and send ModData to all Buffs of a specific Player.
Key=BetterChatNotification
JsonData: Make a String Field with the Key "Message", this is your Formatted Message, if you want to Simulate a Sender (like Plugins) do something like this:
"Revys Awesome Mod: You cannot do that"