Indeed, not crediting all actors was common back than and it is common now, especially for minor parts. There are a few actors that were not credited in Myrt and Marge, and I noticed that during my first viewing. Nevertheless, I am not saying that the actress herself did not perform in the scene. I am merely trying to confirm, so I'll keep looking. I am trying to get in touch with other researchers in academia who might know anything. Research can be tremendously frustrating at times, especially when faced with dead-ends. Thank you for your time.