Perhaps I can add a bit of clarity to this discussion. My Grandfather, Hascy Tarbox, 1918-1991, never considered himself any sort of rival with Orson. The show business world was of zero appeal to Hascy I, and that is why he did not persue such a path. Fame was not one of his aspirations, for Hascy Tarbox was without pretense, and he never was one to seek the fleeting glory of celebrity.
When Orson was a student at the Todd School for Boys, in Woodstock, IL, Hascy's future in-laws, Skipper(Roger) and Hortense Hill, my great-grandparents and the Todd School directors, defacto adopted Orson as one of their children. This was a relationship that lasted until Orson's death in 1985. Following Skipper's death in 1990, my father, Todd Tarbox, aquired scores of tape-recorded telephone conversations, that span many decades, between Hortense/Skipper and Orson. Skipper recorded almost all of his telephone conversations, but the Orson tapes are particualrly touching, as Orson contunues to seek the advice and mentorship of Hortense and Skipper into the 1980s.
If there was any "rivalry" it would have been a sibling-type rivalry between Orson and Skipper and Hortense's own children, Betty, Joanne (Hascy's wife), and Roger.
The notion that Hascy Tarbox and Orson Welles were bitter rivals is a myth. Orson did publicly, and perhaps privately too, speak of a perceived bitterness, but there was no such actual animosity on Hascy's part.
I hope this information is useful.