D/L'ing Castle MP w/Map Pack Purchase

I purchased the Map Pack when H4 first came out. I’ve downloaded, played and deleted both Crimson and Majestic because they were so bad. I want to dowmloaded castle to see if it’s any better, but I can’t seem to download it all by itself. The “store” within H4 requires that I download all three of them again. Is this really necessary or can I download only Castle?