I appreciate Myko's clarification about Tom Steele. I had looked up material on the stuntman from that time, who is also featured with a listing at Memory Alpha. I thought about including it in our article but felt that I was going to over-complicate the story here. I'm not certain that the Tom Steele listed on the 11/21/66 PR is the same Tom Steele who did stunts and is pictured as having made an appearance in "Bread & Circuses" without credit. It's definitely possible. I do think that the Carey Foster listed on the PR is the young woman seen sitting at the table with Masters and her assistant. There is a Carey Foster listed at imdb with a handful of small, likely background, roles in productions around that time, usually playing an uncredited "girl" in a scene. And of course, that assumes that imdb listings are accurate, which is always a roll of the dice.
And I honestly don't know much about the people who would regularly work on the original series as BG - aside from one man named Roger Holloway, who worked as a standin and extra on the show. I only know him because my father worked with him a bunch of times in the 1970s and introduced him to me on set as an actor from Star Trek, telling me "He played Mr. Lemli". (I was cast as one of Roger's kids in a sci-fi comedy pilot called "Space Force", where they were doing a gag that alien families were being transported aboard that were completely identical. Roger's family unit of mom-dad-brother-sister was given Roger's look at the time - a mop of dark hair and a bushy 70s moustache - something that was applied to me, to the mom and to my "sister" for the shot.) I did meet a few of the regular SI's and BG from Next Gen when I worked on Voyager, but I haven't seen those guys in eons at this point.
What we do know from that PR is that a Tom Steele and a Carey Foster participated in scenework as speaking performers, but were never credited or included on any other paperwork that we can find. The PR is a bit odd on this, in that the listing for Foster looks directly connected to the BG section - there's one extra who was upgraded to SAG later in the morning and then dismissed when the rec room scene was done. The listing for Steele, is odd because it has a bizarre in time of 2:00, but the same outtime as Foster. I believe that in-time to be a typo and that Steele was in the same scene as Foster and released at the same time. The only other option would be for Steele to have been brought in during the afternoon, and for his dismissal time on the PR to be a typo, which frankly doesn't make any sense. So from what we have, I am inferring that both of them were in the deleted Rec Room scene between Spock and Lazarus - whatever it was they did has been lost - this was not part of the material scavenged by Roddenberry for his Lincoln Enterprises material and recently re-purposed with the "Roddenberry Vault" release.
It's not uncommon to see background players getting upgraded to speaking roles - but usually there's more of a record than what we see here. On various shows I have worked, whenever someone was bumped up to cast, they'd get a credit. The situation here is one where they were simply paid for the upgrade and that was it. That would not be the case with stunts, but there's nothing in the Rec Room that would call for stuntwork, particularly from a young woman sitting at one of the tables. I doubt the Concordance's take on this, for the same reason that you do.
The full story of what happened with these two upgrades is apparently lost to history now. The people involved are long gone from the business (and many from the planet itself), and the few survivors (including Robert Brown) are unlikely to remember who was upgraded to speaking roles on a day on TV shoot over 50 years ago. The best shot we have at this is the basic documentation - the callsheets and the PRs. And if I could get my hands on it, Bob Justman's production board - but even that board wouldn't note anything about extras being upgraded.
What made the research work here interesting was how much went wrong and how they were able to keep going and just shoot SOMETHING. The materials for many 3rd season episodes are readily available but are frankly not that interesting, simply because they just record fairly mundane days. (I might be interested in looking at what happened on "The Tholian Web", just because that one went off the tracks and wound up with its director, Ralph Senensky, being fired midway, but most of the 3rd season record is a sad routine, as discussed by many of the people who were there.)
What got me interested here was the realization of how wrong the THESE ARE THE VOYAGES timeline is. I'm not joking about Cushman getting this stuff upside down and backwards. And that was only one example. We could get into some really fun stuff about the producing deal they made with John Meredyth Lucas, which was also quite interesting, and even about how Lucas stepped in and covered for Ralph Senensky on Yom Kippur - something Cushman doesn't even include in his accounting of the relevant episode.