You are just trying to redefine a species as any number of things that can be interbred with any number of other things. This isn't what is being discussed. Look up the definition of species (closely realated subsets of species which all carry the same genetics as the overall species, just different dominances). You don't have the A, B, or C anyway.
You realise that by this definition, you would consider A and C to be the same species, even if they can't interbreed!
You're still engaging in a speculative fiction here. Living species are living species, not imaginary ones that live nowhere except in speculation. Just go out and demonstrate your hypotheitcal process with real living things and get legitimate biologists to classify the result as a new species. I will accept that.
IF I take the time to do the research, and I find an example of a plant that has been crossbred a few times, will you accept the resulting crossbreed as a new species if:
a) It cannot crossbreed with at least one of its ancestors, and b) it is fertile?
You implied in your earlier post that you would not.