Have you tried bud pollination? I figured you would, but still.

If I were you, I'd start with whichever decaloba you have that is the most morphologically similar and work your way down the list. If one of the ones you have doesn't do the trick, get more of the species you don't have. ;-)

I.... Kinda have to get 'em to bloom first.
Just like "when will the seed sprout" it's a waiting game- And who knows if they ever will, let alone at the same time.