There used to be some but I think they are non working anymore, e.g.:
https://www.esoui.com/downloads/info...orUpdate5.html
You could try to use an alternative chat addon like TOM, if it provides usage of TOM's chat window and standard chat window at the same time.
You'd have to test it please.
https://www.esoui.com/downloads/info...Messenger.html