For the record, the Rotten Tomatoes site lists the airdate as being January 19,1976 (assuming the week beginning), with guests being Dick and Pat VanPatten, Dick Clark and Kari Wigton, plus Gary and Janet Burghoff.
As for ABC not permitting that to happen, I can see that; but thinking of how Allen Ludden and Bill Cullen (for example) appeared on TT at times while hosting shows on non-CBS networks, I could see it happen in Clark's case. I'd sometimes hear Bert Convy mention the hosts shows, but not the networks, and later on not mention the shows at all. I DO recall Jody Donovan and Richard Dawson appear while he was hosting FF, but Convy would introduce Dawson as "from Match Game."
UPDATE: I checked the webpage markgoodson.fandom.com and found the VanPattens and the Burghoffs, but Liz Torres and Peter Locke instead of the future Mr. and Mrs. Clark listed.