I really think that you have to take them all, the JAA states different learning objectives on each subject, so even if the subject is the same, you could be asked slightly different things.
I'd rather take the 14 ATPL exams, it would take some extra effort, time and money, but I guess it's much better than doing 9+7+14= 30 examination papers (consider also that the CAA don't examine you for free).
Best luck.