There was another episode where she got a job in the restaurant upstairs, and her voice is heard calling down to Norm from above.
It’s up to the OP, but personally I think that voices from offscreen ought to count as an appearance.
The voice on the tannoy at MASH appeared
Charlie speaking over the intercom appeared
Carlton the doorman speaking over the entry phone appeared
In my opinion.
And by the way, there was a Carlton Your Doorman animated pilot which is a definite appearance.
