Therin of Andor wrote:
According to a friend who once found the "TAS Writers' Bible" in the donated research archive (ie. the special science fiction collection) at the Paley Library at Philadelphia's Temple University. (It's a non-circulating collection, but anyone with a legitimate excuse can get permission to browse through specific items.) Essentially, it's a TOS bible with an extra page or two added - there was a little hand-drawn map showing the location of Cait in the Lynx constellation, and another section briefly describing Arex and M'Ress.
Later, Lincoln Enterprises were selling the Arex and M'Ress "biography" sheets, and it's possible those were written by Alan Dean Foster, although no author is credited on them. Other details on M'Ress (parents, siblings, past career highlights) can be found in ADF's expanded scenes of "ST Logs" adaptations, but there are errors re Arex. He describes Arex as having three eyes, in one sequence, and looking over a "feathered shoulder" in another.
That would seem to establish the earliest origin of the "Caitian" term, at the very least.
And it would make sense if Alan Dean Foster wrote the bio sheets, since he was also the author of "Passage to Moauv" and "The Crier in Emptiness" (Power Records, 1975). "Passage" identifies M'Ress as a Caitian, and although Arex never appears, "Crier" features a triple-keyboarded musical instrument identified as an "Edoan elisiar."
I believe it was possible. If the series lasted another season, the B (or C) characters might have enjoyed a spotlight episode, just to pump up the minor characters. Filmation productions were not shy about writing episodes of that kind, as supporting or even comic relief characters would get "their shot" in scripts from time to time (ex. Bat Mite, Masters of the Universe's Urko, Bravestar's Fuzz, et al).
Do not ... EVER ... mention Bat-Mite!