I think to be a spinoff, the character on which the spinoff is based has to have been developed as part of the root show.
For instance, Mork was featured as part of the Happy days plot (a really stupid one as I recall, I think they planted him there for the sake of spinning him off.) anyway, he then took his character to colorado and his own show. Same character, different situation, same delightful comedy.
Frasier is another gleaming example, as is the Jeffersons.
Tiny toons were never on the loony toons, the muppet babies were never on the muppet show,
and although it’s a fine show in it’s own right, No character on King of the hill was featured in Beavis and Butthead. Although Hank Hill has the same voice as Anderson; maybe that’s where
And The simpsons, I don’t think count either because they were animated short features of the Tracy Ullman show, but they were not characters created by Tracy Ullman.
But maybe, because Hank Azaria does some of the voices for the simpsons, and was a player on the Tracy Ullman show, I’m not sure if it counts if like Matt Groening was a writer for Ullman HMMM… anyone know about that?
I still think that in order for it to be a spinoff, it would have to have been about a recurring sketch, like Mama’s Family was to The Carol Burnett Show.