Barring sheep babies, I wonder how David Jacobs arrived at the surname "Ewing." It's a pretty unusual name.
GUNSMOKE ended in 1975 after a record twenty-year run, but the color episodes (nine years of them) went into syndication in the mid-to-late-'70s as Jacobs was writing his DALLAS pilot script (finished 10 December 1977, I think).
Leonard Katzman was on board to be the line producer, with DALLAS to quickly commence filming in late-January 1978... And Katzman had produced the last four seasons of GUNSMOKE, those color episodes going into reruns at the same time, and actor Roger Ewing (who just died a few weeks ago), although only on GUNSMOKE for two brief years, was in the first color episodes syndicated.
Maybe Jacobs caught some of those repeats, saw the name "Ewing," and thought it was unique and went with it. (Although Katzman's GUNSMOKE episodes were a little bit later).
Just a theory, perhaps hairbrained.