"Who Are You?"

During the 50's and 60's television programs rarely ever gave the real names of the subjects in true stories. There was a disclaimer at either the beginning or end of every program that read: "The stories you are about to see are true. The names have been changed to protect the innocent." Or "The events you have just witnessed are true. Only the names have been changed to protect the innocent." I remember well when names and other personal information was never shared. With thousands of public viewers it was priority to keep the people anonymous in order to prevent people from finding them and harassing them, ESPECIALLY back then when there were far far less people open to the possibilities of paranormal events. So Alice Mason and Laurie Warren were not the real names of the girls. This was not just the case with One Step Beyond. All television programs that dealt with real events had the same disclosures. Names were always changed. Most celebrities had fake names too, some still do.
There are so many cases where the spirit of a dead person temporarily took possession of a living person's mind that unfortunately it would be very difficult to sift through them all looking for this specific case. Also unfortunately many researchers have tended to assume they are all demonic possessions instead of some being possession by the spirit of a deceased human and so the cases are grouped together under that label.
Personally I think that after the death of her body, "Alice" saw the waning condition of her mother and temporarily occupied the mind of "Laurie" since "Laurie" was an easy subject to occupy as she was in the process of dying from scarlet fever. Were I come from we call that a "walk in".