I don't think you can... RHS is probably making a mistake in letting anitum be a separate entity from adductum. I'd still keep it as a variety. Also I guarantee no small amount of people claiming to use adductum and actually using adductum v. anitum.
I'm a lumper, not a splitter, and generally say the same thing about besseae and dalessandroi. They may be different, but they weren't different in the eyes of RHS or breeders at the beginning. They are totally interbred at this point. Too late to put that genie back in the bottle, on either side of the argument.
For fun, compare the Johanna Burkhardt awards and the Wossner Black Wings awards.
