Monica, you are always pushing the limits of what this system can support, and I am glad for it because it gives us new perspectives on how the database should be designed.
I don't know about this plant in particular, but it sounds like a new selection or variety that has not yet been registered as a cultivar. The bigger question for us is, I think, if we want such a plant in the database. If so, then I think we should use the cultivar field for this purpose, and the plant can be edited later if they ever change the cultivar to a registered name.
If you have other ideas, I'd love to hear them.