I don't know how close the 2226's would be physically to each other, but with the 4648 cabinets there is a destructive interference at 817hz which means crossing over below 800hz. Since you are running the midhorn starting at around 300hz, I would say you would be pretty safe there. What crossover are you using for the pair of 2226's? Single coil won't cut it as the 2226 is a high inductance driver, might need a 2nd order here????? Maybe Wayne will chime in on this!
Ron