Sorry to be late when asked a question, but it has been answered. Emma Cook is not related to a plicata.
The trouble with some luminata TBs is that they have hardiness problems in New England. If I were crossing those (which I am not as I only hybridize medians) I would put their pollen on a very hardy plicata & follow the line of hardy results. the pattern would eventually show up on a very hardy plant. Much easier than breeding horses as you don't have to find a good home for those that don't work out.
