I thought there was a made for TV movie that had him searching for a kidnapped illegitimate daughter. Or am I remembering wrong?
Just checked Wiki: Movie number two, Gunsmoke: The Last Apache (1990), had Learned reprising the role of "Mike Yardner" to divulge that Matt sired her daughter, who is now a young woman named Beth.
Yeah I saw that one, never did figure where the daughter came from.