How about this.
Instead of saying that you can't buy the Hanger - Advanced Jem'Hadar Attack Ship unless you have the Jem'Hadar Attack Ship. How about this instead?
In you have the Jem'Hadar Attack Ship, the cost for the Hanger - Advanced Jem'Hadar Attack Ship is at a lower price, say 50% less. And by all means, allow people who isn't lucky enough to get a Jem'Hadar Attack Ship the capability to purchase the Hanger - Advanced Jem'Hadar Attack Ship.
I agree, Seriously, To many people spent their hard earned paychecks on getting these dreads just to have you block them from the best part about owning a Jem'Hadar dread. In fact, it doesn't say anywhere on the Hanger in the Dilith store that you even NEED the Attack ship so I spent a little extra to get the Dilith for them just to be told by some random stranger "you can't do that". Have it in your hearts to release them to the General Public of Jem'Hadar Dreadnought Captains.