It would be unlikely that a female of one type (say Western) would be interested in a male of another type (say tricolor), but there have been some examples where rules fly out the window when snakes are kept in captivity.
Look at cornsnakes and Cal kings. Nowhere in nature do they meet, and yet, the captive-made crosses are now common. Look at Carpet pythons and Green Tree Pythons.. who would have thought it would be possible for those to cross.. and yet someone did it at least a few times. Same with blood pythons and ball pythons (totally different continents, and it worked.)
So it might be possible, but I'm sure not easy.
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Mark 