I think it would be cool to be able to have a "beastman" team consisting of minotaurs, bull centaurs, and regular beastmen. If there is any reason why these two teams shouldnt share a mixed team lore wise I would appreciate knowing what that reason is, as I dont know much about the warhammer lore. Thank you for your consideration.
Bull Centaurs are the creation of the Chaos (stupid Big Hat) Dwarfs and their own god (Hassar iirc, something like that) and have nothing to do with Beastmen, Minos and other assorted Chaos races. (As an aside, the original Chaos [non-stupid Big Hats] Dwarfs did associate with Beastmen etc and had Boar Centaurs, but they were dropped as a race between 2nd and 3rd ed Blood Bowl, and Boar Centaurs never officially made the pitch.)
Dwarfs and Chaos Dwarfs hate each other, and would never be on the same team.